Originally Posted by
bisonrav
Combine your avios from BA doesn't give an option to transfer out of IB. Try it and see.
Probably Avios.com works.
No but the question was about BA>IB transfers which are straightforward.
You can (theoretically) transfer out of IB>BA if you don't have a BA household account. If you do (like me) then transferring to Avios.com first does the trick (for now).