I am in two leagues that have been waiting to fill for over a month. Right now, one has 9 openings and the other 7, though the numbers have fluctuated up and down. I've heard that when worlds cannot fill, they sometimes will combine worlds to make a new one.

At what point will they combine worlds? Do they have to sit for two months? Three?
When hey combine worlds, do the owners keep their teams and players, or do they generate new ones?
If by some chance, both of my worlds are merged with each other, do I get to pick which team I keep? Would I get a refund for the other one?

Thank you.

They won't combine worlds automatically, the worlds have to request it from CS. They do seem to require unanimous or near unanimous approval from owners before they'll  do it.  You can keep teams and players, but all pre-merger stats are lost, as well as any trophies you may have had in your case from that league. I have no idea what they'd do if two worlds shared an owner.

The owner would have to pick a team and un-reserve the other.  That's part of the process.    

That said, AL has 23 owners in one world and 25 owners in another. That's a lot more than 32.   Owners would have to agree to dump their teams to get to that level.   Good luck with that.

It might be a grand total of less than 32 if there are enough owners who have teams in both worlds.  For example, if there are 23 in one and 25 in the other, and 16 people have teams in both, then that would be a grand total of 16 + (25-16) + (23-16) = 32.  Just sayin', because if owners with teams in both have to drop a team, then those owners only count as one team total.

You'd still be asking people to drop teams that they may have invested a lot of time (and money) into developing.  Doesn't make it any less of an issue.

a better idea would be to find a 3rd league with openings and merger the 3 worlds into 2, that has been done quite a few times sucessfully, recently.

I forget who it was(mchalesarmy?) but it takes a lot of work to do it.    My guess is there aren't that many owners in worlds needing 10 who are willing to put in the effort.