Is it possible to associate an itinerary with a OWSapphire account (QF Gold) and choose better seats because of this status, and then credit the miles and TPs to a new BA Blue account?

I've recently moved to LHR from SYD and would like to switch to BAEC as a result. With lots of hopping around Europe for ski trips and hiking planned, the additional weight allowance would be nice to have! I have a few longhaul J flights coming up on BA that are currently associated with my QF Gold account to ensure I get good seats.

Now the seats are reserved for me, can I swap the flights over to my BA Blue account and start accruing TP? I should make Silver by November.