My friend and her ex share care of their 7 year old daughter. My friend has raised concern over her daughter and her ex, father of the girl, sharing the same bed. What are the law regarding this

Where? Is this public housing?

Illegal? Probably not. In appropriate? The child should have her own bed for several reasons, one of them being getting a good night's sleep.

Is this every night, or is it just every other weekend when she goes for a visit.

As mentioned, public housing rules do exist and vary on this subject.
It could be possible ammunition in a custody battle, but there are no laws that I know of specifically pertaining to it.
I know people who shared bedrooms (not beds) with parents well into puberty with no ill effects, and there are some famous people who have said they did too. It was a more innocent time however, and if people couldn't afford more bedrooms, that was what they did. Now people sleep on the couch more.

What are the law regarding thisHello miss:

The law doesn't address the minutia of daily life. It's not against the law, but it isn't a good idea.

excon