Anonymous wrote:God OP that is really horrible. I am so sorry. And you ALREADY moved.
Definitely a restraining order and notifying the school, maybe even the activities if you are not there with your children. When one's notifies a school, I wonder if it ok to include a picture of your wacko mom. I just know that some people are better with faces vs just names.
NP. This post notes what I came here to add--you need not only to ensure the school knows but also to ensure that all activities are aware that she must not pick up either kid. If the kids do sports or dance or art or any activity outside school, you need to talk to the people running those activities, as well as provide documentation of a restraining order and yes, I'd add a photo of your mom.
The incident at school is a huge red flag, so take it seriously. Get a restraining order but also take the effort to go see and talk to the teacher and principal with written notification (drafted by a lawyer who helped with the restraining order) and a photo. The school front office secretaries need to know too, because they're the ones (not teacher or principal) who release kids when an adult comes and says "I'm here to get Sally."
Our DD danced for many years and I can see how, just for an example, it could be fairly easy for a familiar person to pick up a kid in some casual places like studios during class changeovers, or at the sidelines of sports fields, or in a community center. That's why you also must talk -- not just once but with reminders -- to your DDs. "If grandma comes and says that dad or mom told her she can pick you up--you must not leave with her. Even if she says WE said it's OK." I really would get a counselor ASAP to work with you on how to talk to your kids so they understand that they cannot ever believe grandma if she comes to get them.
Do you post about your kids on social media? Could mom see things like where they're going to be playing a sports game, or when a recital will take place--? I'd be careful to stop posting any advance details of where the kids might be.
Your mom is clearly seriously mentally ill. It's sad, but protecting the kids comes first.