My kids are due to stay at PIL one night this weekend. They stay about 3/4 times a year and look forward to it. I was telling DS1 about it this evening and it came up in conversation that MIL locks them into their bedroom (all three in one room) at night in case they sleepwalk and fall down the stairs. DS1 is 5 so I took it with a pinch of salt as I thought maybe she just pretended she was doing it to stop them coming out of the room. I asked DD (7) later and she told me the same, she says she hears the key turning in the lock and if she needs to go to the bathroom she calls MIL to come up and hears the lock opening. I will ask MIL in a nice way if she does this as she may be only pretending. But DD says she hears the lock turning and I don't see why she would give the excuse of possible sleep walking unless she was really locking them in. Aibu to be furious about this? Their room is upstairs in a dormer while PIL's bedroom is downstairs. I would be so worried if there was a fire and the kids couldn't get out or any number of emergencies. Btw my kids are aged 3,5 and 7