guardianship of disabled cousin then he was adopted

I live in IL. Ok here is the confusing situation:My mother who has taken care of my disabled cousin for most of his life is now facing a problem with his guardianship and custody of him as he has mental disabilities i believe he has the ability of maybe an eight year old.My mother is stated to have legal guardianship of him in the adoption papers that my grandparents who are now deceased had done. This guardianship would have had to have been done in KY, and the adoption was done in IL. Would that guardianship have to be redone when they moved or does it matter? Also when my granparents adopted him did that make my mother's guardianship invalid? Someone please help!