I was reading Pamela Caunt's book on sweetheart brooches "Military Sweethearts" today and bar brooches are definitely considered to be sweethearts, I think its a coincidence that tie pins are a similar shape.
And looking at Chipper's excellent album the idea of multiple buttons possibly representing family members is very similar to this Australian badge.
http://www.britishbadgeforum.com/for...ctureid=146810
Rob