How much fighting is normal for sibling kittens???

I have five 13 week old kittens that I have in my spare room that I am trying to find homes for. I have 2 boys who have been neutered, and 3 girls who are being spayed next Wednesday. They've been at a friends place being fostered there, and were loving it. Now they're in a smaller space and are going crazy.

2 of the kittens are spoken for but aren't going to their new home until next week when the girl gets spayed.

The kittens are getting quite aggressive when they're playing. They are very well socialised, but they are hissing and growling at each other when they play and they seem to be getting really annoyed. There's always at least one kitten who wants to play, and will attack the other kittens constantly until I get frustrated and put that kitten in the bathroom on its own until it settles down.

I'm away over the weekend, so DH will be taking care of them, and probably won't notice when the play is getting too rough.

Do I let them be and sort out their issues, or just keep them separated so there's less fighting?

I've never interfered unless there's a risk of hurting themselves, like a plate/glass falling on their heads when they bump the leg of the table during a scuffle.

If you can separate the boys from the girls, I'd do that for the time being. It could be that the girls MAY be starting to show signs of heat and the boys are reacting to it cause they smell "different".