Sorry to say a 55 gallon is too small for a Heni or a Tang. The Heni needs a lot of swimming room, a very active fish. The same for a Tang. 2 of them is a 55 would raise the stress level.
That being said, if there is truly an upgrade a year from now, I would leave the Heni to itself until the upgrade is done. You could always add a Tang after the fact if the tank is large enough. What size tank are you shooting for?
, welcome to the forum.
To answer your question, just about any Tang should get along with a Heni in a large enough tank. Especially if the Butterfly was added first.