Let's call her Mean Girl.
Just so you understand, DD (8) is perfectly able to deal with Mean Girl's ministrations, but the incident concerned was a bit foul, and amongst DDs pet hates.
Mean Girl licked her hands and wiped them on DDs face and jacket. DD handled it well and told her off, and said if she did it to anyone else she'd get a teacher.
However, DD came home and asked me to speak to Mean Girl's mum so she'd never do this again, in her words, "It made me feel sick".
I'm happy to do this, Mean Girl's doesn't in any way intimidate me, but....
Mean Girl is obviously a bully for a reason.
Her mum, while not physically abusive, does IMO ignore her, run her down, belittle her, and generally favour her son by her new partner, never attends sports days, exhibitions, etc, and in my heart of hearts I kind of feel for the wee girl - she's not pleasant, but you just feel like she needs some love.
Me wading in with her mum is going to certainly bring down ire upon Mean Girl's head, but not doing so is going to mean disregarding a specific request from DD for my intervention.
WWYD?