Adult and child email mixup

My child’s account has the child’s email listed as my adult email. When I try to type in my email as the parent email and his as the child’s I get an error message. I think this is because the email on the original account was a grandparent’s and I tried to change it to his email not realizing it would assume an adult account. I need to get this straightened out so that his email is in the child email and my email is the adult email. I’m having a lot of trouble because he doesn’t want a new account where he will lose his friends and connections on his previous account. I had to factory reset the VR to get the grandparents info off and update it to mine. It won’t even let me add my kids previous account back on the Vr.  Can someone help me please?