For retailers whose bundles look fine online and wrong everywhere else

Bundles and Kits: Making One Product Made of Several Behave Across Every System

A bundle is easy to sell and hard to account for. The store shows one product at one price. The warehouse needs to pick four items. The ERP needs to reduce four stock records, the ledger needs to know how much of the price was revenue for each, the activity statement needs to know how much of it carried GST, and when the customer sends back one item out of four, somebody has to decide what that one item was worth.

Most bundle problems come from the bundle being defined differently in each system, or defined properly in one and not at all in another, rather than from a broken connection. This page covers the design decisions that keep bundles consistent: which kind of bundle you actually have, which system owns its recipe, how its price is split, and when the native bundle feature in your platform is all you need.

Book a Bundles Call (03) 9003 0111

Bundles in Numbers

2 models

Virtual bundle or pre-built kit

They need different stock, cost and assembly handling, and many catalogues contain both

Lowest component

Sets how many bundles you can sell

Availability is calculated from parts, never stored as a separate number

3 common methods

For splitting a bundle price

Relative standalone price, cost plus margin, or fixed component prices, chosen with your accountant

4 places

A bundle usually has to be defined

Online store, POS, ERP or inventory system, and any marketplace listing

Four Decisions That Determine Whether Bundles Work

Each one is a business decision first and a technical one second. Leave any of them to default settings and the systems will each make a different choice.

Is it a virtual bundle or a physical kit?

A virtual bundle exists only at the point of sale: the customer buys a gift pack, and the warehouse picks the three separate items from their usual bins. A pre-built kit is assembled in advance, carries its own barcode and its own stock count, and the components were consumed when it was built, not when it was sold. Treating a kit as virtual can mean its components are deducted twice, once at assembly and again at sale. Treating a virtual bundle as a kit means somebody has to run phantom assembly orders. Most catalogues have both, and every bundle needs a label saying which it is.

Which system owns the recipe?

The list of components and quantities, the bill of materials, has to live in one place. Usually that is the ERP or inventory system, such as Cin7, Unleashed, NetSuite, MYOB Acumatica or Business Central, because that is where stock and cost live. If the ecommerce bundle app also holds its own copy of the recipe, the two will drift the first time someone swaps a component for a seasonal variant, and nobody will notice until the stock count is out.

How is the bundle price split?

A bundle sells for one price, but revenue, margin and GST all need to be attributed to components. The method has to be chosen deliberately and applied the same way everywhere: at the time of sale, on refunds, in reporting and on the activity statement. Leaving it to whichever system happens to post the order means three different answers to the question of what the mug in the hamper earned.

What happens when part of it comes back?

A customer returns the faulty kettle from a breakfast set and keeps the toaster. The refund amount, the item that goes back into stock, and whether the remaining items are still sellable as a bundle all need rules. Decide them before launch, because your customer service team will otherwise invent a new answer each week and your margin reporting will absorb the consequences.

How Bundle and Kit Integration Actually Works

Six mechanisms. A simple catalogue needs two or three of them. A catalogue with kits, hampers, mix and match and marketplaces needs all six.

Component lines

Virtual bundles exploded at order

The storefront sells the bundle as one line. When the order reaches the ERP or warehouse, the integration explodes it into its component lines using the recipe held in the owning system, so pickers see the real items and stock is reduced component by component. The bundle line is kept as a parent reference so the customer invoice still shows one product at one price. This is the right model for most gift packs, starter sets and multi-buys, and it means no assembly ever has to be recorded.

Assembled stock

Pre-built kits and assembly orders

For kits that are physically put together in advance, such as a boxed hamper or a sealed tool kit, the ERP raises an assembly or production order that consumes components and creates finished kits with their own cost. From then on the kit is an ordinary stocked item to every channel. The integration publishes the kit quantity, not a calculated figure, and optionally publishes a second, calculated figure for kits that could still be assembled from loose components if your team assembles to order.

Sellable quantity

Availability from the scarcest part

For a virtual bundle, the sellable quantity is the minimum across components of on hand stock divided by the quantity per bundle. Illustrative example: a coffee starter kit needs 1 grinder (40 on hand), 2 filter packs (50 on hand, so enough for 25 kits) and 1 bag of beans (120 on hand), so 25 kits are available. Sell 20 filter packs individually and the kit drops to 15 without the kit itself ever being sold. Recalculating on every component movement, not on a timer, is what stops the bundle overselling.

Rule based boxes

Mix and match and build your own

A build your own box has a rule rather than a fixed recipe: any six items from a pool, or one from each of three groups. The order arrives with the customer choices as line properties or child lines, and the integration converts them into real component lines in the ERP. Availability is checked per eligible item rather than per box, so the storefront hides choices that have run out instead of hiding the whole box. The pricing and allocation rules are agreed once and applied to every combination.

Revenue and GST split

Price allocation to components

The bundle price is spread across component lines using the agreed method, commonly relative standalone selling price, so each line carries its share of revenue, its cost of goods and its tax code. The integration does the arithmetic consistently, rounds to the cent with the remainder placed on a nominated line so the total always equals what the customer paid, and stores the allocation against the order so a later refund can reverse exactly the same figures.

Zero priced lines

Free items and gift with purchase

A free tote bag with orders over a threshold, or a sample included with a skincare set, is still stock leaving the building. The integration adds it as a zero priced line with the correct SKU so it is picked and deducted, carries its cost of goods into the margin of the order that triggered it, and posts it to a promotional cost or marketing account if that is what your accountant prefers. Without this, free items vanish from stock records and appear only at stocktake as unexplained shrinkage.

Bundle Scenarios and How They Should Flow

Task	Traditional	Done Properly	Notes
Shopify bundle sold online	Bundle SKU sent to ERP, no stock moves	Exploded into components from the ERP recipe	The bundle app and the ERP must not both hold recipes. Pick one owner and have the other read it.
Pre-built hamper at Christmas	Treated as virtual, components double counted	Assembly order builds hampers as stock	Assembly also locks the cost at build time, which keeps margin reporting stable through the season.
Same bundle sold in store	Staff scan each item, bundle price applied by hand	Bundle scanned or chosen in POS, components deducted	Shopify POS, Lightspeed and Square handle this differently. Some need the bundle as its own product with a barcode.
Mix and match box of six	Choices typed into an order note	Choices become real component lines	Line properties have to be structured data, not free text, or the integration cannot read them reliably.
Gift with purchase over a threshold	Popped in the box, never recorded	Zero priced line, stock and cost recorded	Set a cap on promotional stock so the offer turns itself off rather than consuming core stock.
Food hamper with wine and a mug	Whole price coded to one tax rate	Price apportioned between GST-free and taxable parts	The apportionment method needs your accountant to sign off. The integration then applies it every time.
Customer returns one item of four	Refund amount decided on the phone	Refund uses the stored allocation for that line	Consumer guarantees still apply to a faulty item in a bundle, so the policy has to allow an Australian Consumer Law remedy for it, which can be a part refund.
Bundle listed on a marketplace	Listed with a fixed quantity, oversells	Calculated availability pushed to the listing	Marketplaces usually treat a bundle as one ordinary listing, so the calculation has to happen before the feed.

Where Bundle Integrations Quietly Go Wrong

Two copies of the recipe

The ecommerce bundle app says the starter set contains a blue cup. The ERP bill of materials was updated to the green cup when blue sold out. Orders pick one thing and deduct another, and the variance appears weeks later at stocktake with no obvious cause. Decide which system owns every bundle recipe, usually the ERP, and make the other system read it or receive it through the integration. Audit the two against each other weekly until you trust the process.

Kits treated as virtual bundles

If a hamper is physically assembled in November and the integration also deducts its components when it sells in December, every component is reduced twice. The reverse failure, selling an assembled kit as if it were virtual, leaves kits sitting on the shelf in the system while components are reported short. Label each bundle as virtual or assembled in the product master and make the integration branch on that label, not on a guess.

Bundle discount absorbed by one line

Some platforms apply the entire bundle discount to the first line, or to the bundle parent, leaving components at full price and the parent at a negative value. Revenue by product becomes meaningless, margin on the first component looks terrible, and a later part refund pays out the wrong amount. Allocate the price explicitly with an agreed method, store the result against the order, and use those stored figures for every subsequent event.

GST on mixed bundles coded at one rate

A hamper containing GST-free food alongside wine, a mug or chocolates is generally a mix of GST-free and taxable components, and coding the whole price as taxable overpays GST, while coding it all as GST-free underpays. A reasonable apportionment method is needed, commonly relative standalone selling price, or cost plus each item’s usual margin. The ATO’s mixed supply ruling, GSTR 2001/8, includes a hamper example and warns that cost alone may not be reasonable where mark-ups differ between items, and the classification of individual food items is itself detailed, so your accountant should choose and document the method. The integration should then apply it consistently and keep the workings.

Free items never deducted

Gift with purchase lines are often added by a storefront script that the ERP never sees, so the stock disappears without a record. Over a busy promotional period this can be a meaningful amount of product, and it also understates the real cost of the promotion. Every free item needs a SKU, a zero priced line on the order, a stock deduction and a cost of goods entry, so the promotion can be judged on what it actually cost.

Reorder points ignore bundle demand

If forecasting only looks at sales of a component as a standalone SKU, it misses every unit consumed inside bundles, and a component that mostly sells inside a gift set will look like a slow mover right up until it runs out. Component demand has to include exploded bundle sales and assembly consumption. This is also why bundle availability should drive purchasing alerts: the scarcest component is the one that stops a whole bundle from selling.

How Yes AI Approaches Bundles and Kits

A bundle register before any build

We list every bundle, kit, hamper, multi-buy and promotion you sell, label each as virtual, assembled or rule based, record which system owns its recipe and how its price is split. The register is a spreadsheet that usually takes a few days to build, and it often shows bundles that are already defined differently in two systems.

Native features first

If your ecommerce platform bundle feature or an off-the-shelf bundle app already sends component lines to your ERP correctly, we will say so and leave it alone. Custom work only earns its place where the native option cannot handle assembled kits, mixed tax, part returns, marketplaces or POS consistently.

Explosion, allocation and sync hosted by us

Bundle explosion, price allocation and availability calculation run on a managed cloud automation layer we operate, with record level logging of every recipe used and every allocation made, and alerting when a bundle arrives with no recipe or a component goes missing.

Component level reporting

Sell-through by component across standalone and bundle sales, margin by bundle using the stored allocation, gift with purchase cost per promotion, and a weekly recipe audit between systems. The figures your buyers need to decide which bundles to keep.

From Bundle Chaos to Consistent Kits

Five steps. The highest volume bundles typically flow correctly within four to six weeks, depending on how many systems are involved.

Build the bundle register

Every bundle, kit, box and promotion, labelled virtual, assembled or rule based, with its recipe owner, channels where it is sold, and current handling in each system.

Agree allocation and tax rules

Price allocation method, rounding, GST apportionment for mixed bundles, free item treatment and part return policy, agreed with your accountant and written down before anything is built.

Decide native, app or custom

For each bundle type, confirm whether the platform feature or an off-the-shelf app covers it end to end. Build only the gaps, and route those through the integration layer.

Build and test with real orders

Explosion, assembly handling, availability calculation and allocation tested against a month of real historical bundle orders, including refunds, part returns and promotional free items.

Monitor and audit recipes

Alerts for unknown bundles and missing recipes, weekly recipe comparison between systems, component sell-through reporting, and new bundles added through the register rather than ad hoc.

FAQ

What is the difference between a bundle and a kit?

In integration terms, a virtual bundle is sold as one product but stocked and picked as its separate components, so stock moves only when it sells. A kit, sometimes called an assembly, is physically put together in advance, has its own stock count and cost, and consumed its components when it was built. Platforms use the words loosely, so the useful question is not what the product is called but whether anyone assembles it before the order arrives. That answer decides how stock, cost and availability are handled.

How is bundle availability calculated?

For a virtual bundle, divide the available stock of each component by the quantity needed per bundle, round down, and take the lowest result. The scarcest component sets the limit. It must be recalculated whenever any component moves, including standalone sales, receipts, transfers and adjustments, otherwise the bundle can oversell even though its own product was never touched. For assembled kits, availability is simply the kit stock on hand, plus optionally what could still be assembled from loose components if you build to order.

Should the bundle recipe live in Shopify or in our ERP?

Usually in the ERP or inventory system, because that is where stock, cost and purchasing live, and a bill of materials there can drive assembly orders and component demand. The storefront bundle feature or app is then a presentation layer that sells the bundle and either reads the recipe or passes the bundle through for the ERP to explode. The exception is a store with no ERP, where the ecommerce platform is the inventory system. What matters is that only one system holds the recipe.

How should GST work on a hamper with GST-free and taxable items?

A bundle that combines GST-free items, such as many basic foods, with taxable items such as wine, a mug or confectionery is generally treated as a mixed supply, where the price is apportioned between the GST-free and taxable parts using a reasonable method, commonly relative standalone selling price, or cost plus each item’s usual margin. The ATO’s ruling on mixed supplies, GSTR 2001/8, includes a hamper example, and individual food classification has its own rules, so your accountant should choose and document the method. Our role is to apply it identically on every sale and refund and keep the workings.

How do we handle a customer returning part of a bundle?

Use the price allocation that was stored against the original order. If the kettle in a breakfast set was allocated a set share of the bundle price, that share is the starting refund for the kettle, and the stock goes back as a kettle, not as a bundle. Your policy may adjust this, for example removing the bundle discount on a change of mind return, but a faulty item still attracts the remedies under the Australian Consumer Law regardless of how it was sold. Agree the rules once and have the integration apply them.

Do bundles show up properly in our POS?

It depends on the POS. Some, including Shopify POS for some bundle types, can sell a bundle and deduct its components natively. Others need the bundle created as its own product with a barcode, with the integration exploding it afterwards, or need staff to scan components and apply a bundle price rule. Before building anything we test the exact bundle types you sell in your actual POS, because the native behaviour varies by platform, by feature and sometimes by version.

When is the native bundle feature or an app enough?

More often than people expect. If you sell virtual bundles on one storefront, the ERP receives component lines or can explode the bundle itself, tax is the same rate across components, and returns are rare, the native feature or a well regarded off-the-shelf bundle app is usually the right answer and custom work is wasted money. Custom integration earns its place when you have assembled kits alongside virtual bundles, mixed GST bundles, POS and marketplaces selling the same bundles, gift with purchase at volume, or reporting that has to show component level margin.

Get Your Bundles Defined Once and Behaving Everywhere

Book a call. We review how your bundles, kits and promotions are set up across your store, POS, ERP and marketplaces, tell you where the native features are enough, and give you a priced plan for the rest. The review is yours either way.