Daughter sharing room with unrelated boy

My 6 year old daughter lives with her mother. He mothers partner of 6 months has moved in and he has his children to stay over every weekend.

He has a 8 year old son and a 14 year old daughter.

The eight year old boy stays in my daughters room and his daughter stays downstairs.

I feel it is inapropiate for him to be sharing a room with my daughter as they are of the opposite sex, not related and have only known eachother a couple of months.

I have tried to raise this with my ex but she just gets mad at me.

Any advice?

that is your opinion, rightly or wronngly and I know how you feel.
But unfortunately as much as you might try to stop it, she will resist even more.
Best advice is be aware of anything your daughter might say to you, at the end of the day if the kids are happy then thats best, but if your daughter has concerns she may tell you, then its time to act.

At what age does it become illegal?
They only have a 2 bedroom house so I can''t see this situation changing and feel the older they get the worse it is?

At the ages they are now, its not too much of an issue. As they get older they won''t want to share so your ex will have to sort something out.

There is no law that states that mixed siblings shouldn''t share a bedroom, the Housing Act 1985 s(328) makes provision under the rules of over-crowding for mixed siblings to no longer share a bedroom when one of them is aged 10 or above.

Can you suggest an alternative to the current arrangements at your ex''s house?

I have tried to suggest alternatives but I get my head bitten off for mentioning it.

They are not siblings, if they were I would not have a problem with it.

It just really worried me given their young ages and the fact that they barely know eachother.

I used siblings in the much broader context of the word - if your ex and her partner marry, then they will be step-siblings.

I can understand your concerns, have your children expressed any issues over the bedroom sharing?