The sibling who set up the iPad
When their father got an iPad, his older son set it up — entered the Apple ID, arranged the settings, stayed signed in "in case there's a problem." It was kindness, and for three years it was nothing more. After the father died, the same account was still open on the son's own devices: the photos, the messages, the health data, and the Notes app where their father had kept a running list of the changes he meant to make to his will. The younger children never knew the access existed.