I have this disorder. Makes things...difficult to say the least. I find keeping myself stable, and away from the triggers that cause me to switch helps a bit, but is not always possible. 1-3 switches a day seems to be my limit for being "comfortable" before gaps in memory yet real bad, and emotional control is thrown right out the window, of course leading to more switching lol.
working out a system amongst yourselves also helps to keep things in order, getting everyone on the same page/goals helps out too. Writing little notes about what happens if you suddenly switch in the middle of things...lots of ideas that take a while to actually put to practice.