How to update PO routing code once PO is placed

Hello there,

seek your advice to see if there is a way to update PO approval routing code once it is placed. The business scenario is that the PO has got approval threshold limit setup at the time PO is placed. and it will go through the P2P process. However in case the invoice amount is not the same as PO amount, it will trigger to amend PO amount and it will invoke the existing PO approval routing code while business is asking for any changes on PO amount has to routing for approval.

I can have different P4310 version to assign different PO approval routing code for the PO amendment, however it will NOT overwrite existing routing code. Is there any way to overwrite PO approval routing code?