When a customer buys products that belong together, a mountain bike and pedals, a jacket and matching pants, or eyeglass frames with prescription lenses, they don’t think of them as separate SKUs. They see them as one complete purchase.
But when these products arrive separately, shipped from different locations on different days, that sense of completeness breaks. What should have been a single moment of delight becomes a disjointed experience.
That’s why linked and complementary products need to be treated differently in order management. In this blog, we’ll look at what these products are, why they’re challenging to fulfill, and how intelligent routing helps retailers preserve the experience customers expect.
What are linked and complementary products?
Linked or complementary products are products that are sold together and meant to be fulfilled as one. They may be functionally dependent (like eyeglass frames and prescription lenses) or connected through merchandising (like a “shop-the-look” outfit, suit jacket and matching pants).
These products are usually configured within the same order under an item group, a logical bundle that defines which products belong together and how they should be routed. For example:
-
• Mountain Bike + Pedals + Helmet + Bike Wash
-
• The order includes all four items.
-
• The bike, pedals and helmet form an item group that must always ship together.
-
• The bike washing kit can be shipped separately if unavailable at the same location preventing the whole order from being held.
-
-
• Eyeglass Frame + Prescription Lens + Sunglasses
-
• One order includes all three items.
-
• The eyeglass frame and prescription lens form an item group that must always ship together.
-
• Sunglasses can be shipped separately if unavailable at the same location.
-
-
These relationships matter because they preserve the integrity of the purchase.
When expectations aren’t met
Most order management systems treat each SKU as an independent unit when routing. That works fine for simple orders, but breaks down when products actually have relationships with each other.
Let’s take the example of the Eyeglass Frame + Prescription Lens pair. A regular OMS might decide to ship the frame from one store and the lens from another, optimizing for distance. But from a customer’s perspective, that logic makes no sense. They can’t use one without the other, and receiving them separately feels careless.
This disjointed routing causes:
-
• Inconsistent delivery timelines: Parts of a set arriving days apart.
-
• Higher shipping costs: Multiple shipments for what should be one.
-
• Operational chaos: Returns, reships, and manual intervention to correct mistakes.
-
• Frustrated customers: Especially when they’re paying for complementary products as a single purchase.
In short, the problem isn’t with inventory, it’s with logic. Retailers often have the stock to fulfill the order correctly, but their routing doesn't understand the relationships between products.
The ideal routing for linked and complementary products
The right approach starts with understanding how the products relate to each other, and defining rules that protect those relationships.
In an ideal scenario:
-
• Item group splitting is disabled to prevent splitting linked or complementary products (like frame and lens).
-
• The rest of an order can split to allow independent products, like sunglasses or shoes, to ship separately if needed.
This kind of routing logic balances fulfillment optimization while keeping the integrity of the order intact.
Linked and complementary products in HotWax Commerce
HotWax Commerce’s Order Routing App is built to handle these complexities with simple configurations. It allows retailers to define item groups, apply custom allocation rules, and automatically route orders based on product relationships.
When an order includes linked or complementary products, the OMS identifies which products must stay together and which can be split. The routing engine then evaluates all fulfillment locations to find the one that meets both inventory and relationship criteria, so that the right products always ship together.
The result is simple but powerful:
-
• No mismatched deliveries.
-
• No customer confusion.
-
• No manual rerouting.
Just the kind of order experience customers expect when they buy products that belong together.
The promise of shipping together
Linked and complementary products may look like a small detail in a complex retail system, but they carry outsized importance. They define how complete an order feels to a customer.
By giving routing logic the intelligence to recognize these relationships, retailers protect the experience they’ve worked hard to design, one where every product arrives as part of a complete story.
* * *
With HotWax Commerce, that promise isn’t left to chance. Get in touch to learn more about intelligent order routing.
