I raised 3 girls and one boy. At least 2 of my girls were sharing a room until the oldest 2 were grown and moved out. By then they were teenagers. It was always a challenge for the girls who were sharing because they had less privacy. I would let them use my room for a phone call or homework, etc. if they really wanted some privacy.

On the upside, my children are all best friends and very close to each other. Do you have an office or den or family room that isn't used all the time that you can set up a special place for them to have some private time like that? It helps.