I've e-mailed avios.com, trying to explain that I wanted just one sector to qualify for avios.com credit to ensure the 500 Avios quarterly bonus, the other sector qualifying for BAEC Avios and TPs.
We seem to be in standard message mode, though. They've asked for info on PNR, avios.com membership no, routeing etc etc and raised the issue with BA as a missing miles enquiry. They passed the info to BA on whom the final result depends.
No sign of that yet. Possibly unfairly, I suspect I will get avios.com credit for both sectors with a consequent deduction of BAEC Avios and TPs.