When I brought up the subject to the mother, all I said was that, "I'm not sure if **** is playing or not but she's been saying (insert what I typed) a lot recently." That's all I said on the subject before it turned into an argument between my bf and his mother about me.

I also don't think his sister is a liar. She fibs at times and me and my boyfriend have both caught her doing it. She'll ask one of us for snack, we'll ask her to ask her mother first, and she'll say she said yes even if one us clearly heard her say no. After checking in with the mom it's confirmed she was lying. Kids do this all the time, I did this as a child. It's not a defining part of her personality.

We've been dating for 4 years and I occasionally watch over his sister. I don't discipline her and try not to push direct commands on her because they have their own parenting setup. I also almost never give her a snack/treat without asking her mother first. I like to have permission to give her food and will usually ask myself or send a text if I'm babysitting.

I said it in the post but if she did have her moms permission, that meant she was awake and could give her the chips. I made a mistake by thinking her mom was asleep but it did seem like it and the mom never said anything although her door was open and is right next to the kitchen.

I mentioned it in another comment but I studied child development and I work a lot with kids. I don't take any of this personally. I know she's a kid and she's not out to get me. We get along all the time. She really likes me and when she gets upsets it's because she's a child. The problem for me is that it's been happening a lot more often recently and it seems like something that most people would address. Like if a child was mocking. I'd expect most people to say, "Hey don't do that, it's not nice when me mock others." Mocking isn't terrible, but it's usually discouraged. Just like comments that would read as mean if they weren't from a child.

I also don't eat her food or use her things. I have my own food and things. And I usually share them with her. She says these things unprompted.

I generally do not try to intrude on her parenting at all. I don't even tell her daughter what to do directly. If she's do something she shouldn't be that involves me. I explain the situation, gently ask her leave, try to redirect her, and then eventually get her brother's attention so he can say something or get her mom.

Does that change your response at all, you've seemed to misread me.