Advice for giving teens privacy in their shared bedroom?

We have a total of 6 kids living with us. 3 are biologically mine and 3 are my nephews that we took in after the death of their parents. We have a small 4 bedroom home. Right now my older two nephews (15 and 13) share, my son (6) and youngest nephew (8) share, and my two daughters (8 and 4). We don't have issues with the younger 4 but the older two have started bickering a lot about having to share a bedroom. They didn't mind at first. We think it had to do with both of them grieving the loss together. They wanted to be close and often slept in the same bed. That was over 2 years ago now and both are moving forward with the process of grieving. They will never be completely over it but they are happy more often than not and have adjusted beautifully to their new lives. They both are active in school. Both play sports and one also does music. One is involved in student council and the other is president of a school club. We are very proud of them. I don't want this post to come across the wrong way or like they are angry at the world.They have been fighting a lot lately about their bedroom. We have set up a privacy curtain but both complain about the other having to walk through their space. One is a lot more tidy than the other and hated having to walk through a mess (unmade bed, books scattered across the desk, some papers on the floor) to get to his side but now complains about not having privacy because his brother now has to walk through his side of the room. I can't win. They also argue about having friends over and sleepovers. They feel like the other brother is intruding no matter what. We tried to set up a schedule but with 6 kids going in 6 different directions I left it to them to manage and it would just result in arguing. For a while I had them go to their friends houses instead but both revealed they felt like I didn't really want them and their friends at the house so we started inviting them back again. I told them they had to work with me on this and they agreed but a few weeks later we were back where we started.What can I do? I know both boys are getting older and need some more privacy time but I don't know how to manage it. Both get home from practice and want to lay in their own beds but if someone has friends over then it is WW3 in our house.Both boys have a therapist. They don't have regular meetings anymore but go on an as needed basis. Both went on their mothers birthday a couple weeks ago. via /r/Parenting https://ift.tt/2N6Szrs