R.T.
S.,
I am not sure if it is appropriate for me to reveal my profession, but after I read your story, I feel I must. I am a clinical psychologist and a consultant for the Department of Children and Family Services. Unfortunately, I see situations like this too often. I do not have much to offer in regards to smoothing things over with the sister-in-law but that does not seem to be what's important here. I am extremely concerned about what happened to your daughter. Until you know what happened, she should never be around those children unsupervised. You did not mention if the 10 year old is a boy. I am wondering if that child was around your daughter. I know your daughter may be upset about not seeing them for the holidays but her safety MUST come first.