How orders reach your 3PL.

What the order looks like

A customer buys "Hair Care Set" (2× shampoo + 1× conditioner, bundle price $45):

The fulfillment order (what your 3PL's Shopify integration imports) lists the same component lines. Inventory decrements on the components, never on a phantom bundle SKU.

Why this matters: the failure mode we designed against

Most bundle apps work at the presentation layer: the order contains one "Bundle" line, and either your 3PL can't map it to pickable items, or the app edits the order after creation to swap in components. Post-order editing races your 3PL's import: if they pull the order before the rewrite lands, they ship the wrong thing. Peak-season order volume makes the race worse exactly when mistakes are most expensive.

Solid Bundles uses Shopify's Cart Transform API: the expansion happens inside checkout, so there is no moment where the order exists without component SKUs. There is nothing to race.

Provider notes

• ShipBob / ShipHero / Shipmonk / Amazon MCF: standard Shopify order import picks up component lines automatically. No kitting configuration needed unless you physically pre-kit.
• Pre-kitted stock: if you physically pre-assemble bundles and stock them as one unit, a fixed-bundle app isn't what you want. Create a normal product with its own SKU instead. Solid Bundles is for pick-from-components fulfillment.
• Barcode workflows: component lines carry the variant's own barcode fields; scanners resolve normally.
• Partial refunds/returns: refunds hit specific component lines, so your 3PL's return processing maps 1:1.

Multiple warehouses? Your kits stay whole.

Stock a bundle's components across two or more locations and Shopify's default routing will happily split the order — one parcel of shampoo from Warehouse A, one of conditioner from Warehouse B — or pull everything from a single location and drive it negative. Native Bundles has no lever to stop this; most bundle apps don't either.

Turn on Ship from a single location for a bundle and Solid Bundles adds a Shopify Fulfillment Constraint: every component of that bundle must be fulfilled from one location. Your customer gets one parcel, and no location is driven negative because it was missing a piece. If no single location can ship the whole bundle, checkout is blocked with a clear out-of-stock message — the order is never mis-shipped; it simply isn't taken until it can be filled correctly.

This is pure routing. It reads your locations; it never writes an inventory number, so there is nothing to drift. In the app, each ship-together bundle also shows how many complete kits are sellable from a single location — the honest count, not a pooled total that looks bigger than what can actually ship as one parcel.

Verify it yourself

App → Verification runs real test carts and shows resulting totals per market. For a full dry run: place a test order (Bogus Gateway on a dev store, or a 100% discount code) and inspect what your 3PL portal imports.

Running an ERP as well? The operations guide covers reconciliation, the zero-write inventory model, and a one-hour evaluation script.