Given that any successful Jacobite would himself be a Catholic descended from Catholics, I can't imagine the ban on Catholic marriages would stay whenever it happened.
Didn't Charlie flirt with Protestantism later IOTL? Maybe if he tries something with it in 1745... (though I'm not sure that would work with his father is still around). No idea how plausible that is.
Most likely it's theoretically nullified but if the Jacobite king has any sense he'll be treading very, very carefully regarding religion.
A fair point, I know he came to London and secretly converted to Protestantism in 1750, if he did something like that during the 45 campaign, that could make his life slightly easier?
Yeah, but how would Charles converting in '45 work when the Jacobite claimant they're nominally fighting for is his still staunchly-Catholic father (maybe if James is dead?).
There's also the fact that BPC's brother ended up a Cardinal IOTL, so how would he react to his brother converting?
I can definitely see bonnie prince Charlie or even James II eldest son Charles duke of Cambridge saying thatHe could pass it off with a quip: "If Paris is worth a mass, London is worth not going to mass."