"I'm not a baby!"

My SIL has an almost 5yo and I notice when we are around each other that she and my brother will tell the 5yo that she is "acting like a baby" if she is whining or acting out. Also, if 5yo isn't doing something she should, but my 2.5yo is- they will say something like, "Look, [2yo] is eating her dinner and she is just a baby!"I play with my 2.5yo with her baby dolls and sometimes I will scoop her up and rock her like a baby, playfully in the moment- like I do with her babydolls (I will sing rock a bye baby). One day I picked 5yo up and did the same to her (I wasn't really thinking about how SIL/Brother talk to her) when she wanted me to hold her and she got very angry- almost like a trigger- and yelled, "I AM NOT A BABY!" Of course, I said I was sorry but it made me concerned at her reaction :( I said something like, "I'm sorry, I know you aren't really a baby, I was pretending. I won't do it again."I am not sure why it rubbed me the wrong way or if it is a common thing people do. I am venting because I feel like it is a kind of bullying tactic or something... I don't really know.I do notice when 5yo is around the younger ones, she regresses slightly- attention wise. Like she sees the type of attention the smaller ones get and wants the same, I play into it a little bit when maybe I shouldn't?Or if 5yo does something like fight over a toy with my 2.5yo they will tell her that shes older and needs to give the toy up when my 2.5yo doesn't know any better. My 2.5yo understands the concept of "taking turns" and does not get a free pass to snatch from the 5yo, so I will intervene and tell my 2.5yo to share/take turns. This leads to the 5yo telling on the smaller ones frequently, I think looking for equal treatment. Which turns into SIL/Brother telling the 5yo to stop being a tattle tale. I don't really feel like it's fair for the 5yo to get all the responsibility of being "mature" when she is around the little ones because she is still only 5yo.I try to treat them all equally when they are around me. Sometimes I will say, "[5yo], [2.5yo] can't play with that because she will break it. I know you want to share and that is very kind of you. Can we put it up on the counter where you can reach it, but will keep it safe from [2.5yo]?" That is really the only time I refer to the age difference.Sorry for the word vomit and tangents, I just feel for the almost 5yo. via /r/Parenting https://ift.tt/2wnrJoK