We are expecting a baby girl and have my SO's little guy (5y/o) half the time. Messy divorce and custody battle so we expect them to try and make gender difference an issue as we are in a 2 BR condo.

They will have separate beds (bunk), and change in the bathroom. I know CAS standpoint of once they are in school, but that isn't law is it?

Any help you can offer would be greatly appreciated.

I don't know what you are worrying about. You only have his son half the time. A bunk bed for your new baby is down the road somewhat. Baby doesn't haven't to be in the same room for quite some time; will be in a crib in your bedroom. Is that not so?

There is no law about opposite siblings sharing a bedroom. It isn't done on moral grounds if the siblings are entering puberty and old enough to know what their bodies are all about.

A lot of what goes on in a divorce has little to do with law. I agree that you don't have anything to worry about now, but do think this is a question for your lawyer, who knows more about what your SO's ex is like and what his/her lawyer is like. This question does come up in divorce a lot, as one parent tries anything to obstruct shared custody. To save time and money, I'd work out a plan for a specific year.