Time in a multiverse

If the multiverse theory is true (that ours is just one of >1 universe), I'm curious how time would work in it.

On a documentary I saw a few years ago, one theory regarding this says that our universe might have been created when two other universes collided. Another theory says our universe is an expanding bubble in a bubble bath of universes. Yet another says we might be the offspring of a black hole in another universe. And maybe it's a combination, all or some of the above?

Now, to me, as a layman, all of these seem to require time to be not bound by a particular universe. Two universes swinging wildly in a void would need time to be present universally? Same with the bubbles. To know if the bubble is expanding, we need to make a comparison between two points in time. Inside the universe, that's all and well, but outside of the bubble, would we have anything resembling universal time on a multi-universe scale? Multiversal time perhaps?

I'm sorry if I'm not making any sense. Just throwing the question out there, as I've been thinking about it for a few days.

(and still haven't managed to formulate a better question, eh?)