One version of the multiverse hypothesis is that every possibility split creates separate universes. For example, if you spin a coin, then the universe splits into one where it lands heads and one where it lands tails.
I think of it in the opposite way.
When you spin a coin, 2 verses exist (in the future) and when the coin lands (the event) the side it lands on is in the universe that exists and the other verse is now impossible/nonexistant.
The future holds and infinite number of possible verses (a multiverse) but when the events happen, all of the options/verses are eliminated, leaving the one universe that we are aware of.
The way you put seems backwards to me, that after the event happens we are left with a multiverse in which all of the possible events have taken place in multiple verses.
I think it doesn't matter how improbable something was that did happen, because it had an infinte amount of chances to happen(the multiverse), it is now a part of out universe because it did happen, and it's improbability doesn't matter/ceases to exist. This last part doesn't really fit in but I was just thinking how people say that the probability of all this order happening from random events is so impossible that it suggests ID, but I always think about this multiverse when that comes up and that it DID happen however improbable it was doesn't matter. There were infinite chances for it to happen, we're just left with the one event that did happen, no matter how improbable it was.
what I ramble I just typed