Update son's email address in microsoft family account settings

[Rodsman62]

So, not sure if this is the right place to ask this question and this should be easy to do but I cannot figure out a way to update my son's email address in his "child's" account in our microsoft family account. I can manage content, time (on xbox), etc., but I cannot figure out a way to update his email address. I've tried the recovery tools but he cannot remember some key info and I keep getting a "no go" message when I try it with what I do know. I know it can be done because I updated my other son's account email address a few years back. Any help would be appreciated.