Hi, Sally:
Yes, this is a "sticky" situation.
The child is jealous of your DD.
Yes, the Mother and child needs to be confronted.
How to do it?
Ask the Mother and child to meet with you and your child. Tell her what is happening and how you want to address it.
When you meet, state what the issues are, then ask the child these
questions:
1) What happened?
2) What were you thinking of at the time?
3) What have you thought about since?
4) Who has been affected by what you have done? In what way?
5) What do you think you need to do to make things right?
Then ask your daughter these questions:
1) What did you think when you realized what had happened?
2) What impact has this incident had on you and others?
3) What has been the hardest thing for you?
4) What do you think needs to happen to make things right?
Hope this helps.
Good luck.
D.
www.iirp.edu