Daughter says a family friend's daughter pulled her pants down and sat on her

[Nickie2017]

My 7 year old daughter stays at her father's house during the summer and I received a message saying that my daughter was touched inappropriately by my friend's daughter. When I got on the video call with her and I asked her if anyone pulled their pants down infront of her she said no,and then her father told her to tell me about what she told them about the girl. She says the 12 year old would pull her own pants down and sit on her(my daughter's)back or legs and make fart noises. She also brought in the sister saying the sister would tell her to get off.
Here's the thing,I talk to my daughter all the time about what is not appropriate and that if anything happens she needs to tell an adult right away. When we have these conversations, I'll ask if she's seen someone else's privates or has anybody seen hers,hers, if anybody has ever touched her on her privates and she always denies it. She is always wanting to go to this person's house and will even throw a fit if she can't. My daughter is also a tattle tail.. If ANYTHING  happens,she is the first to tell you.I spoke with the sister and she says she's never seen her sister do it(she is the child to go to for the truth). The 12 year old that is being accused doesn't have the mind of a 12 year old. She's a kid in a 12 year old body. My stepson(age 7)hangs around the 12 year old more than my daughter and I asked him if she's ever done anything inappropriate around him and he says no. She also says it happens alot but she hardly ever goes to their house.
I don't want to believe my daughter is lying about it,but none of the story makes sense. I'm keeping her away from the 12 year old until I get to the bottom of it but is there a way to tell if she's making the story up or telling half truths?

[specialmom]

Well, that sure is frustrating.  I sounds more abusive than sexual to me though. The making the 'fart' noises kind of indicates she is trying to be gross rather than be sexual with her. That's if it happened which I guess you are determining.

WHO sent you the message?

Your daughter says it didn't happen. who is saying it did? And is anyone else confirming it in any way?  

I think if it were me, I'd have a talk with my daughter that she is to tell if someone gets naked and sits on her. Period and that it is a rule that this is not allowed. That she doesn't touch naked friends and they don't touch her. Period. Rule.  And then the other family should say the same to the 12 year old.  The "kid in a 12 year old body" part too, remember, 12 years old IS a kid still.  She's still a child too.  If both know this isn't allowed, whether it happened previously or not, it may never happen again.

If I thought from anything you wrote that this was a sexual situation and your daughter was being molested, I'd speak up.  It's inappropriate but I think it could be managed. Child on child molestation is different. That's often a sad situation of the child doing the act to another that had previously been done to them. It's a vicious cycle. If your child were actually molested, I would say working with a child psychologist would be the best choice. But I don't get that sense here.