Transfering to another state for work

Ok so I am relocating to SC for work on April 1st… However since there will only by 8 weeks of school left my EX-Mother in Law has proposed the idea that my two daugthers stay in Charlotte with her until school is completed. Im a little uneasy about this beacause I dont know if she is trying to pull anything slick. Here are my questions:

  1. COuld this pose a problem if she or their Dad want to try and get custody from me?
  2. Should I have her and my ex sign something stating this is just temporary and that no legal action for permanent custody will ty to be taken?
    3… Would it look bad on me to take them out of school with 8 weeks left if my ex wants to try to take me to court for custody?

A grandparent does not have standing to sue for custody unless a parent is proven to be unfit.
I do not think leaving the children with your mother in law is ideal, however it will at least allow them to finish out the school year uninterrupted. I would suggest you enter into a temporary parenting agreement that states the children are remaining in Charlotte only to finish school and that custody will be determined between you and the father at the end of the school year.