I imagine you looked at moving your Avios from BA to EI (or IB) rather than redeeming Avios through BA?
Of course :-). I can do that and it’s straightforward. The issue is the TFC (see above) where I get hammered on short routes due to the evil YQ “carrier imposed charge” (=fuel surcharge).
The difference between Avios and UA for the TFC per-pax on my journey (LHR-SNN return) is GBP 59.75 - and there’s five of us. I know I’m slightly cutting off nose to spite face by devaluing my MR points, but it’s the principle and the fact I don’t want to hand over £300 for a “free” short haul flight in Y.