Warning or Alert on Approved PO

Hi,

is there any workaround to set alert or warning on approved PO that if the GRN is already done, system wont allow user to change anything in PO.

Actually we need to block any amendments on approved PO. I know if you change anything on approved PO, it will create revision and again it will go for approval. but sometimes workshop user try to change without returning the GRN. and without returning GRN you can not edit/remove line.

Thanks