Wedding room disaster?

If these are young girls (under 10) why can't the 1 from your side have a bed, and the 2 sisters from his side share the other? Can his family not trust your family to care for their kids a single night? That would solve the problem of the second bed going to waste, and give the aunt and uncle on his side a night alone, since they will be paying for their room out of pocket. I'm sure the kids would have a blast too, and it would pretty much solve the problem. When kids are little, sharing even a small bed isn't really an issue, and is often really fun for them.