Processes in Microsoft 365 for setting up Office apps, redeeming product keys, and activating licenses.
Hi, @mike summers
She needs to resolve the account recovery issue first. If she can no longer access the old recovery email, she can follow Microsoft's official account recovery process here:
Alternatively, if she cannot recover that old account (or wants to skip the hassle), she can simply create a brand-new, fresh Microsoft account using an active email address, and then accept your Microsoft 365 Family invitation with that new account instead.
Should you need further information please let me know.
Click "Add comment" to let me know.
Thanks!