Hi there. I can see you completed the add steps and it keeps saying he is already in the family, yet he does not show up. The usual cause is a mismatch between account types or profile details, so the system flags the join as complete, but the member stays hidden.
Lets try a few quick checks. Confirm your son is using a personal microsoft account, not a school or work account. Open his account’s profile and make sure the birthdate and region are set correctly and age based consent is completed if required.
In Family Safety on the web and the mobile app, check if the view is filtered to organizers only and switch to show all members. Ask him to sign in to account.microsoft.com and verify he accepted the invite from the same alias you sent to, not a different email alias. If you manage multiple family groups, ensure you are looking at the right group. Try a clean browser session by clearing cache or using Inprivate, then refresh family safety. A few questions to help pinpoint this. Is he using a school or work account. Did he accept the invite on the same email you sent. What is his age on the account and region. Do you have more than one family group.
Chard