An integrated threat protection solution designed to detect, investigate, and respond to cyber threats across Microsoft 365 services.
Hi John,
please ask your family member to go directly to https://family.microsoft.com, sign in using the exact email address you invited, and accept the invite from the pending banner instead of clicking the email link. Gmail addresses are often already linked to an existing Microsoft account, which can cause sign‑in or account creation issues. They should also try signing in at https://account.microsoft.com and use the Forgot password option rather than creating a new account, as this is a known reason why Family sharing can fail.