Can I link other accounts than The British Airways Club to Finnair Plus?

No, at the moment, you can only link your British Airways Club account to your Finnair Plus account. Iberia Plus, AerClub, Vueling Club and Qatar Airways Privilege Club also use Avios, but you cannot currently link these accounts with Finnair Plus.

However, you can link your Club account to your Qatar Airways Privilege Club or Iberia Plus account if you have those accounts.