Did anyone actually find Sulik's missing sister? It seemed to be a side quest that I could never solve. You first meet Sulik in Klamath in which he tells you about his sister that was nabbed by slavers while out trading. It is possible in the later stages of the game to wipe out the slaver's guild in The Den but no sight of her though. It seems at this point that the game sort of trails off at this point. She isn't in the holding pen in NCR or in the Stables outside New Reno that leaves only one place....The Enclave.
It's obvious that the Enclave goons have taken her since they need "mutated stock" to practise the FEV virus on and aren't above buying from slavers and gangsters (eg: the final mission for the Salvadore family New Reno) but even with this in mind I never could find her.
Any thoughts?

Killap's restoration patch restores the quest in which you finally locate her. It also includes Sulik's village as a visitable area.
Basically, you find her in a cage guarded by a bunch of slavers, along with many other slaves. Precisely how she got there is open to question, but you can rescue her from there once you find her.

That thing was confusing me too back in the day. That quest was never finished in the original game, probably because of time constraints, but has been restored and finished unofficially, as Prator said.