Auto generation of reservation for stock item procurement

hi ,

How do we implement an automatic generation of reservation for store and spare materials at the time of Goods receipt. This requirement for spare and store material (stock).

e.g

User A creates a Purchase Requisition for stock material "xyz" without account assignment then it convert into PO and when finally material arrives at the warehoouse now user B will do the GR while doing the Goods Receipt material should automatically reserve for User A

Looking for a positive support

Thanks in advance

Ather