Splitting party :
a) I think you mean for movement : you have to manually *drag* a portrait away from the other portraits. You will see a chain animation between the portraits.
( it is counter-intuitive, annoying and I really want them to change movement to a simple select character 1 and/or 2, 3, 4 or all. )
b) A character in sneak will not be auto-followed by those who are not in sneak.
c) If you mean changing companions, that is done at the Long Rest Camp, but I think you know that.
