Thanks Jerry, i will give buying a thought. I had gone through the links you suggested.
David - I din't think combine my Avios would count, but the agent on the phone was positive it would count. I wasnt sure of the Avios balance while on the call, so checked soon after the call.
The problem is that we have a HHA, and I have all the earning partners points i.e. Hotel, Tesco, BAA etc.
Your first edit does seem interesting i.e. one providing the RFS eligibility and the other providing the voucher. Will test that tomorrow.
Th Amex transfer is an issue as she currently has a negative points balance due to a refund, so although she has been using her card (although sparingly) the points do not make it to the BAEC due to the negative balance. But that negative balance is near to 0 now and I can top up my oyster and make it positive tomorrow. Any idea if Amex consider making a one-off special transfer rather than the usual monthly transfer?