Legal Question in Family Law in Massachusetts

I assume you mean your ex has primary custody of your two children. You would have to file a Petition for a change in custody with the probate court. While your children are old enough to have their desires considered, there has to be a good reason.

Likewise your ex would still be entitled to visitation.

I suggest you contact an attorney for assistance in this matter. I do not handle custody battles but would be happy to refer you to someone.