my step daughters are 17stb18, 14stb15 and 9.
They live with DH and go visit BM.

We have a big house and the upper floor is all theirs. Now the thing is I moved into his house that he inherited from his very rich grandfather but it wasn't always like this. When BM was married to DH, all house was DH's and BM's and the girls had rooms for themselves. Now DH and I aren't "allowed" to go up there. Well DH doesn't want to so he gave them the whole floor to use,while I would want to use that floor too because it could be much more useful than what they use it for, but he thinks it's alright that it stays theirs. So basically I am not allowed up there because they don't want it and he thinks that wish should be respected.

Now there are 6 rooms there and they only need 3, of course. But they get 6 rooms and their own bathrooms, each. and a little kitchen. While BM and DH were married they used the remaining 3 rooms but when they divorced Sds took over and it's all theirs now.

That whole floor is a mess, the huge space is unused and the older two girls barely have any contact with their father,let alone me.
There's a door and stairs from outside so they don't even pass through our floor at times.

they generally ignore me, and act respectful to their father but in the end actually ignore what he said and go for what they want.
He doesn't see that anything should be fixed.

For example, SD14 is going out. they're talking about how long can she stay out and he says you can stay till 22:30.. and she's like OK. But when she's going out the door, she says ''I'll be back at 23:30" and he says fine. He doesn't even mind.

I think he should have a stronger grip on her but he doesn't. He thinks that the freedom he gives her is alright and that nothing needs to be changed.

But they are often disrespectful in a kind of hidden way and it's bothering me.

What would you suggest?