Kitting & Manufacturing
Substitution groups
Let any of several interchangeable SKUs satisfy a kit or BOM component slot. Track which one actually shipped for accurate cost and warranty data.
Why substitutions matter
In real warehouses, a "10mm screw" might come from Vendor A or Vendor B—functionally identical, different SKUs, different costs. Without substitution support, you'd be forced to either run two parallel BOMs or constantly relabel inventory. Substitution groups let you tell ShipWave "any of these SKUs satisfies this slot" so kits and BOMs pull from pooled availability and pickers grab whichever bin is closest.
Defining a group
Go to Admin → Substitution groups → New group. Give it a name (e.g. "10mm M3 screw") and add member SKUs. Mark one as the preferred member—this is what pickers will see first, and what cost will be used in profitability projections when the actual shipped variant isn't yet known.
Pooled availability in kits and BOMs
When you add a substitution group as a component to a kit or BOM, ShipWave treats it as a single slot whose availability =
sum of all members' qtyAvailable. So if Vendor A has 40 screws and Vendor B has 60, the kit sees 100 screws available, not min(40, 60). The kit's overall availability still uses the standard min(component / ratio) formula—the group just changes what counts toward "component."The picker UI
On the pick list, a substitution slot shows the preferred member first with a small badge listing the alternates and their bin locations. Pickers tap whichever one they actually grab and ShipWave records that choice on the order line as
actualVariantId. This is critical for: (a) accurate FIFO cost consumption, (b) warranty/recall tracking if one vendor's part later turns out to be defective, and (c) re-order signals (you want to re-order from the vendor that's actually being consumed).Cost handling
At ship time, ShipWave consumes a FIFO layer from the actually-picked SKU, not the preferred SKU. The profitability dashboard reflects the real cost. If a picker forgets to record the actual choice, ShipWave defaults to the preferred member and flags the line for review.
FAQs
Can a substitution group be used in more than one kit/BOM?
Yes. Define it once and reference it anywhere. Updating the group (adding/removing a member) propagates instantly.
What if the alternates aren't exactly identical?
Only put truly interchangeable parts in a group. For "similar but not identical" alternates (different finish, slightly different spec), use two separate components and let the picker swap manually with a note.
Does this work with serial-tracked or lot-tracked items?
Yes—the picker records the specific lot/serial as part of the same "what did you actually grab?" step. See <a href="/help/kit-returns-policy">Kit returns</a> for how this flows into recall handling.
Will Shopify see the substitution?
No. Shopify only sees the parent kit/BOM SKU. The substitution is purely an inventory and cost concern, not a customer-facing concept.
More in Kitting & Manufacturing
- Kits vs. BOMs: which one should you use?
Understand the difference between virtual kits assembled at ship time and pre-manufactured finished goods built from a Bill of Materials.
- Creating a kit
Build a virtual bundle from existing components. Availability and component decrement happen automatically at ship time.
- BOMs and manufacturing orders
Define a Bill of Materials, issue a manufacturing order, and track labor + scrap as components are consumed and finished goods are produced.
- Kit and BOM returns policy
Choose whether returned kits come back as individual components or as a single re-assembled unit. Lot-controlled recalls handled automatically.