I'm sorry but I still don't understand.
The inbound stock is the sum of quantities of items added to Purchase Orders that are:
- Part of a PO that has any status different from "Received" (for PO free version)
- Or not added to any delivery (for ATUM Purchase Orders PRO)
And this value has nothing to do with backorders.
So, no matter whether you have a back-ordered item or not, the inbound stock won't have this into account for its calculation.
Not sure if what you want to do is a partial delivery (so 5 items arrive first and 2 arrive later) and want to take only the received items into account for the inbound stock calculation. If so, this can be done with our ATUM Purchase Orders PRO add-on.
You can read more about partial deliveries in our documentation:
I hope this helps.