Kgirls doing doubles that engage in girl-on-girl as part of the session  (for the ones that do this, it's almost always included in the reviews because its hot), then ask the booker if one of them would be willing to see you and your lady at the same time.  I've admittedly never done this because I haven't yet met a civvie girl that is as good at sex as two Kgirls, but I had a friend that was able to do it a few times and this is how he found the girl. There may be an upcharge. You should also be well-known by the booker.  There are about a half-dozen sets of doubles right now advertising in LA and OC.  Do some research and then go for it.  I would love to read a MFF review with a Kgirl and a civvie girl.

I heard the girls pay you, so why the question?

Oh, must be bullshit like everything else the little lioness purrs.

http://www.theeroticreview.com/discussion-boards/k-girl-113/ah-the-petulant-insecure-little-boy-----30510?page=1

As usual, dumb luck saves the day.  Have this kinky MILF g.f. She has been asking about an MFF threesome, and I have been trying, and failing to set it up….  Today, I go to an AMP out of boredom, more than anything else.  I know a few of the girls there over the years.  All decent looking Thai girls, from whom I usually get a massage, HJ and BJ.  All the regulars were out today, for some reason.  So I see a buxom woman — great tits and ass, good looking, nice smile.   One thing leads to another and she is telling me as she sucks my cock how she wants to eat my gf’s pussy while I fuck her in doggie, and how she wants to watch me fuck the gf while her tongue is in my ass, etc etc….

I believe her, too, because SHE brought up the idea when I mentioned casually that I had a g.f.    

Will advise.