Because one profile is private, no one else can see the information and cannot 'update' the profile, which is what is done during a merge. Send a message to info @ wikitree.com with the profile that needs merging and they can complete the merge OR have your father complete it, if he is still PM of the locked profile. Depending on the dates on that profile and if it is a living person, he could also 'unlock' the profile, which would allow anyone to complete the merge.