You earn miles on Asiamiles and your loyalty programme is MPC. There's no other way to credit your miles anywhere else with the sole exception for residents of UK. UK residents can opt for MPC but credit miles to BAmiles and not Asiamiles.

You would earn BAmiles but receive no credit towards status on BAEC. In other words, it is strictly a rewards programme for you. Your status would therefore remain with MPC.

Miles earned on BAmiles cannot be transferred (and v.v) to Asiamiles should you leave the UK. Your MPC status would remain with you but your hard earned miles have to stay with which ever programme you had chosen.