Removing Epirus would make Makedon stronger.

But....maybe this could be countered by making Koinon Hellenon stronger as well? For example, what about giving KH Crete at the beginning? And if that's not enough, maybe even give them Thermon too?

Also, maybe, take Pella away from Makedon at the beginning and make it an Eleutheroi city - force Makedon to take Pella back from the 'Epirote Gallic mercenaries' who occupied it under Pyrrhus.