Is it appropriate for a boy of 9 to share a room with his younger soster who is 6?they have different fathers, does this make any difference?I'm looking online for information about this situation for a friend of mine, but I can't find an answer anywhere...

There is no way that they could have their own rooms? Boy's really like to have their boy things and girls really like their privacy. The sexes are so different and it would be nice for each of them to have their "own" space. After 10 the boy needs his space... what about sleepovers and playing with the boys in his room? He can't do that if his sister is there... or visa versa!

If you have no choice... then you have no choice... you could do the bunk beds and make it funky. Maybe a theme that they could both enjoy like space and add glow in the dark stars... floating planets from the ceiling (fish wire and clear pins) and paint the room to that theme with cool stuff in it (desk station for coloring; book shelf for books and each their separate toy box)... maybe the bedspreads could be on red and one blue or something. If you have to; you have to!

Appropriate? That's really a personal question open to all sorts of opinions and lifestyle choices. My opinion is that its fine, pre-puberty.

Legally, there is nothing that states anything about it at a federal or state level. There may be public housing laws in some places regarding it though.

This is in the UK by the way sorry for any confusion

Because these are not your children, I am wondering why you are asking. Is the mother having concerns about the sleeping arrangements?

Has somebody said that it is innapropriate?

I would think that if the mother is having any doubts whatsoever that the sleeping arrangements are bothering her, then the children should each have their own room.

I've never had that problem, but if they were mine, I would be planning for separate rooms in the not too distant future.

I don't think it's a problem or that it is inappropriate at this stage... maybe in a few years when your boy is older... arrange the room so they are both excited about it... if you can't do the separate rooms then you can't! It makes no difference if there from different fathers... they are still 1/2 brother and sister... does it matter if they are 1/2 and not 100%? No.