Overbearing sister in law

I am extremely appalled. Living with my in laws has been peaceful, but when the sister in law comes (Everyday, btw) she is getting too overwhelming. She used to barge into my room every morning when I just gave birth to carry my child down, and she never lets go. She always carries her. My child is coming 5 months. I’ve been holding this in for 5 months. I WFH now, and I was just taking a rest with my child, playing with her letting her watch the tv (yes it’s bad but I control her screen time) she and her son knocked my door loudly, came in without me saying anything, pretend to talk to my child and tells her “let’s go down and play with korkor” and just leaves. I was stunned beyond belief I couldn’t utter a single word. I am at my limit. Someone, please advise me before I go mad. Living in this house has gotten worse overtime.