So in the "old" pantheon I'm referring of course to pre-fall Eldar, so before we were left with just pieces of Khaine and Cegorach running willy nilly.

In a few things I've read it's made mention of Kurnous as kind of a father diety to the Eldar as well as a hunter. In connection to Kurnous it is noted that there are those who walk his path amongst the eldar "outcasts" who travel about the galaxy revelling in the hunt.

Now this is all rather limited in its scope, but could one assume that the Exodites might also find need to worship Kurnous or his wife, Isha, while living in the more pastoral setting of a maiden world?

Also what is the official background on Y'nnead?