I have four DC. Eldest two, DD1 (9) and DD2 (7), share a room, as do the youngest two DS (4) and DD3 (2). All works well at night time. However.... there is a constant afternoon battle between DS and the older 2. He wants to play in their room with them. They say no. On the one hand, I think it is fair enough that they want to have their privacy away from their pesky younger siblings. But they don't usually apply the rule to DD3. So we get the likes of yesterday where DD2 spent an hour designing a beautiful poster for her door saying "Girls only".
DS is the only one of my kids who is completely incapable of amusing himself (unless there is a screen involved), so he takes it all particularly badly. There are also times when DD1 says he can come in and DD2 says not.
DD3 remains largely oblivious to all rules and pretty much does what she pleases. So far she has more or less been given a free rein by her sisters to come in and out because they know policing a rule where she's not allowed in will be more work than it's worth.
So what happens in your house? Should everyone have the right to refuse whichever siblings they choose? Or should it be a blanket welcome or refusal? And what if there are differences of opinions between room sharers? All experiences gratefully received.