Question on character generation

I have been playing and importing (from black pits) many characters. I see a lot of these coming back in the "character generation" list when starting a new game. My question is, when does a character end up in this list? Coz i don't see my last exported black pits character in there, but i do see those few pre-generated ones and many of my own..
Also, is there a way to maintain (remove entries from) this list on iPad? I would like to clean the whole list or at least only keep a favorite few...