Partly for me but could help others with a similar problem.

In Gotham at the moment we just got our 3rd actress for Ivy Pepper (the eventual Poison Ivy) and its explained via ongoing plot (trying to avoid spoilers for anyone not current). In this case if apped I would be using her second actress till more info is known/end of the current season. Would that work and how would actor changes need to be addressed otherwise (pending the canon of course)?

TIA!