Can you STOP mobile receiving from 'Cascade' Qty to different Shipments ?

We are running Release  12.1.3   and preparing to implement  Mobile Receiving in a WMS organization. 

One problem we are having and would like to change is when doing receipts for a specific PO Line number,  if there are multiple shipments for that line it will cascade any extra receipts to other shipment lines.

For Example let say I have  PO # 1  Line # 1  that is for a total quantity of  1000 items, and we have 2 shipments defined of 500 each with a different Need By Date.

If I do a Mobile Receipt - PO Receipt -  for that line and do a receipt of  501 items.   It will receipt 500 for shipment 1 and 1 for shipment 2.    Even if we have an acceptable quantity tolerance of 5% over or under.   We would like the system to assign all 501 to that first shipment.