Even if you manage to change the FFP number away from QRPC back to BAEC I would be very surprised of you flights credit to anything other than QRPC.
Refer to this recent thread for more disappointment...
www.flyertalk.com/forum/british-airways-executive-club/2068353-booking-qatar-airways-using-pc-ff-number-can-you-swap-ff-baec-later.ht