I don't know about your Facebook, but myLog In has a feature (on most status- & comment-forms) that automatically suggests friends & groups & sites when you start a word with a capital letter, which it then completes & links-to when you select it. (i.e. If I'm a Facebook-friend of yours & you type "Jas" into a comment- or status-form, my name will pop-up on a drop-down menu for you to select & let Facebook automatically finish & -link-to) It also does that for family-members---filling-in my brother's info when I type "Bro;" sister's when I type "Sis." But then (as when I write "aunt," "mom," "daughter" etc.) But Facebook doesn't place any notice of that person's relationship to the writer. Why not?
Maybe it only works with "Mother"? I'm not sure and I can't really test it, because my mom doesn't have Facebook, but that would be my guess. No idea, why aunt and daughter shouldn't work though.
Did you Capitalize them? coz I think that's how the auto-fill feature works; you start typing in a name/relationship, it starts to find `em for ya.