User blog comment:Mroddy/Let's Talk: The Cast of Frozen/@comment-1874924-20160427010732

I think Damien being Heather's younger brother is fairly well known, since it was mentioned in the pseudo-canonical text bios on the show's Season 1 website. In the TDA episode, "One Flu over the Cuckoos", Heather is writing her will and mentions her "brothers and sisters", implying she has more than one of each, but none are named.