Hi
You can change PC in master (material) using MM17 or LSMW..
Impact -
You need to consider for open sales orders.. They will continue to have the Old PC.. You need to short close the SO line item and add a new one
Also, the open prod oroders will continue to have Old PC.. See if you can change it.. If not, live with it and it gets corrected from next order onwards
Also, open GR for which MIRO is pending, I think the GR IR account will hit the new PC>. But please test this..
Br, Ajay M