Change the Plant in PO other than PR and RFQ

Hi Experts,

Need help for following scenario

1) Raised PR for 100 Computers for Plant "A".

2) Created RFQ with ref to PR ( Plant flows in RFQ from PR in non-editable mode.

3) Want to create PO with ref. to RFQ for different different plant.

Here system is not allowing to change the plant other than RFQ.

Kindly revert.

Thanks in advance.