What are the laws regarding sleeping in a room with a child that goes to see her father every other weekend and sleeps in a room with his girlfriends son- she is 6 he is 4

First, its not a good idea to piggyback your question on another thread. This can lead to confusion. So I've moved your question to its own thread.

Second, ANY question on law needs to include your general locale as laws vary by area.

Any laws about this are at a very local level and generally refer to public housing.

What is your probloem here? Are you concerned because a 6 yr old girl has to share a room with a 4 yr old boy every other weekend? Do you think something is happening or are you just looking to get his visitation curtailed?

All the times this question has been asked, no one has ever found a state that has a law covering the situation. Public housing, however, does often have very specific rules about it. I don't think you will find a child behavior expert who will find a problem with a 6 year old and a 4 year old sharing a room. You and your ex should discuss in a rational way at what age you will agree is an appropriate one to change that.