I know there is realistically nothing that I can do about this. I have tried to do what I can to keep her at an arm's length or more away from me at all times, but it seems she weasels her way into something every few days lately.

It wasn't bad enough that she was the head of the giant festering pimple of a conflict that went on for over 6 months regarding what school SD would go to and whose residence she would live in after starting middle school. (She and BM told SD she needed to "choose", although SO is already the CP and they have no say in that)

She also has to get involved in everything that goes on in our house, and pump SD for information every time she goes over there, and try to go against every decision we make in our household.

She called SO a few weeks ago and yelled at him because he hadn't taken SD to get her eyes checked when she failed the eye exam given by the school nurse. We had no clue about any of it, and when SO took her in, the eye doctor said she was VERY BORDERLINE for glasses, and a lot of kids fail eye exams given by people not in the opthamology profession.

Then there is tons of petty shit that just adds up.
*Going out and buying SD a new tube of toothpaste because she "lost" hers in her dump of a room, and we told her she could just use the communal one til she found hers, which was not acceptable
*Giving SD literally 100's of hotel shampoo, conditioner, lotion, and soaps (that she now hates and is sick of and complaining about) because she didn't like the items that were bought for the family and we wouldn't take her out and buy items just for her.

And most recently, she came over 20 miles to drop off a box of graham crackers and a gigantic bottle of ranch dressing for SD, because "she wanted them and we wouldn't buy them." WTF? If she would have asked or bothered to look, there was a box of graham crackers there all along. Whole box! And I have bought her ranch dressing, and she uses like 2 tablespoons and the rest of the bottle gets left to rot in the fridge. I was very offended by this "guesture", and I am glad I was in the bathroom when she came by.
I mean, seriously, I come down stairs and there is randomly a bottle of ranch and graham crackers sitting on my table? She tried to use the excuse that SD wanted salads and ranch is the only dressing she likes. Ok, so what kind of salad can you make with dressing and crackers?? Maybe I shouldn't be mad, but if it was me I would have gave it back to her and said "We can do our own grocery shopping, thank you." OR "Hey, next time you want to do our shop for us, let me make you a list." OR "If you wanted to be useful, you could have taken this violin that needs to go be returned to BFE and exchanged for a full size one, since you don't mind driving."
Ok, I am shutting up now.