Adding more than one Instant Bank Transfer account

I would like to add US Dollars from a UK Revolut account via Instant Bank Transfer to cut out on fx fees but the slot for this is taken up by a different bank account.

I cannot seem to find any way to add an additional account without removing the one currently in place.

Could 212 make it simpler and just add a + button to enable adding a second or third account to instant bank transfers?

Apologies if I am overlooking something and thanks in advance for any advice.