Am I overreacting?

My brother, SIL, and their 2 kids moved in with me and my family in 2020. My kids are 5,4, and almost 1. Their kids are 8&10. Today the 8yr showed him where his basket was hidden as soon as he stepped into the livingroom then my 4yr old woke up when I was going to the bathroom and the 10yr old showed him where his was before I got out. I know its super trivial but crap like this happens every holiday and I’m just breaking

It really depends on why they’ve been there that long. Is this a permanent situation? Was this living situation intentional or due to lack of housing or losing a job or something. Kids get excited. You may need to plan your bathroom breaks sooner or talk to the bigger kids that are apparently up before the younger ones. My older sister woke me up every Christmas so that is natural. You need to be ready early with a camera to be on top of holidays , that is your job.