Here is a tip for splitting the camp. If you stand to the far north, so that Kayla is south of you and Shayla is south of her (and Jayla and Tayla are off to the west (right), if you root or otherwise agro Kayla, only Shayla will come to her aid.
Thus, if you can root Kayla, Shayla will run and you can take her on, one on one. Then you can kill Kayla afterwards, assuming you root holds long enough.
Finally, you can then root one of Jayla or Tayla and take on the other.
Do this quickly and you can med up and be ready for Shayla (who should thus pop first) before the others and then just repeat the cycle.
One last tip. As you are gathering necklaces, WRITE DOWN WHOSE YOU HAVE. You woul dnot believe how hard it can be to keep track in your head of 4 rhyming names. Once you have the 4 necklaces, cruise back to Kelethin and grab your reward, but if you don;t write it down you're almost certain to get 3 and then be confused as to whom you need to kill.

Bottle of Kalish
Bronze Main Gauche
Dull Pearl Necklace
Iron Ore
Mangled Animal Pelt
Rough Silk
Rusty Dagger
Rusty Short Sword
Silvril Ore
Tattered Animal Pelt
Weak Larkspur Extract
Weak Muscimol Extract