Hmmm - given we're pushing the sins connection, how about if we have two connections.
First, the original research group, which could have a number of names. I like the idea of calling it a University or Academy, but I'm flexible on the full name. This would be a public group that in theory anyone could join.
Secondly, the university spawned a secret Lissalan cult. Originally founded to try to steal secrets from Thassilon, it can be the reason why we start recruiting specialists from outside our normal circle.
@Gara: best I've got is that Ignavius needed someone who spoke Tian or Tengu in order to decode his book, and tracked you down.