First time posting. My sil (brothers wife) has 1 ds who is 3 and my ds is 4. They live at my parents house so we visit occasionally. It’s been a few months now and Everytime we go, sils ds (my nephew) always wants to go upstairs (in the bedroom) so my ds follows him and my sil takes them upstairs. Several times when I’ve gone up later on to open the door to call my ds to either eat or go home the doors been locked. I then knock on the door a few times while letting ds know ‘it’s time to eat’ or ‘we are going home’ and sil never opens it. I go back downstairs then come back up to repeat what I’ve said above but she still won’t open the door. She eventually does open the door but it’s after a lot of knocking and telling my ds he needs to come down. I'm abit confused as to why she would do this. Her ds and mine are close but they do fight alot too. Me and sil aren’t close at all as she keeps herself to herself. I just want to know what you guys think before I speak to her about it.