My sister and her husband have been happily married for 11 years and been together for 16 years. They have a six year old daughter and 5 month old twins. They have been in the best place this year they have been in the 16 years. Last year in October they bought a house together and my father had to borrow my sister R545 000 for a deposit for the house.

In July she mentioned that the 6 year old`s teacher got dumped by her fiancee ending a 5 year relationship. In August she became friends with my sister and started to turn my sister against her husband and us. She would secretly visit my sister her her office. SHe would organise movie nights for the two of them and keep my sister from her children and husband and us. On Monday my sister told her husband she wants a divorce and we found out that this teacher wants to move in 1 December into their house and live with my sister and the kids and my brother in law must move out. 

First of all, what do we do to get my fathers pension money from my sister?

Secondly, can my brother in-law sue for damages against the teacher?

Nobody could have predicted the current situation as there where no signs for us to do something.

And also the kids always stayed with my parents during the week and over weekend and now she is keeping them from my parents.

And lastly, the teacher and my sister have been spreading false stories about us and my brother in-law to our friends and family.

Please help!