I am playing as the High King of Ireland, who, as an Insular Christian, is required to have 3 wives if I don't want a piety generation penalty.
When my half-sister died, it pushed me into a mental break, and I was given a choice where one of the options was to convert to Paulicianism, another Christian sect. The big difference though, is that Paulicans are monogamous.
If I make the switch, what happens to my existing marriages? Do they get annulled? Stick around? (but don't do it again, buster!) Is this true even when switching to a faith that doesn't allow divorces?
I wasn't willing to risk it (and am playing Ironman) so I did not find out.