Avoid Shipment 80 status when a purchase order has not been received

Hello all!

My client has the following scenarios:

1) Purchase Order --> Shipment number related

If the purchase order has NOT been received the shipment number CAN'T advance to 80 status thru the R4981.

This scenario is working fine.

2) Several Purchase Orders --> One Shipment number

One of the PO has been received, but the others are pending to receive.

Then if I try to update the shipment (R4981), it goes to 80 status.

Is there any setup or a way to avoid this status change?

The client only wants to let the change when all de PO are received.

Best regards.

Carles