Ya the family mailboxes thing was aimed at parent-child or secretary-boss relationships; where you still want to know who actually sent the mail even when it appears as
boss@domain.com
For you the synopsis is back to choices B-E if you want them 100% unrelated with no shares or 'local' account aggregation.
Though you could do some postfix header_checks I suppose:
IF From:
user@personal.com & Sender:
user@company.com REPLACE ....
Postfix manual - header_checks(5)
(But again that's outside the relm for every end-user, hence the 3 RFE's.)