Finnair Plus - How to optimize benefits on AY flight with BA status

Hi

I'll be flying soon several flights with AY and currently I have my BA EC-number marked in the booking and hence I can more easily choose better seats thanks to the OWS-status. However, the Avios yield for the flights is so low and I don't really need additional TP's prior August (no change for BA Gold, silver already secured) so I thought I could collect the points to my AY+-account where they actually yield more points than Avios would.

I can change the FF-number for the booking quite easily, but will the metainformation of my OW status then disappear?

Lounge access etc. is easily handled by just showing the card at the lounges, but thenagain the seat selection, possible op-ups (not likely I reckon) are somewhat dependant on the status.

Or should I wait 'till the last minute and change the FF-number for each flight at the airport, or does that really matter at all?

Book your seats, change the FF number on finnair.com at any time you want, simple as that..it really doesn't matter...op up chances are next to nothing anyway so absolutely no need to think that aspect at all.