For example, growing large enough to upgrade your government to an Empire makes you a cultural union which may make some cultures that you had previously promoted become automatically accepted and so free up a slot.
Does this scenario automatically free up a slot?
So, if I promote something it takes up the slot and if I upgrade the government rank and get a cultural union the slot is free again without me outraging the provinces of that culture?
Or could it be that I get a cultural union, but the slot stays occupied by the culture I promoted before, if I dont demote it?