while I am not a candidate to join in this event (not my thing), I do wonder if the therapists would be uncomfortable with this. you should make sure you pick one that you can speak to openly about expectations.
I find many chinese do not openly agree with same sex actions....this is only based on opinions of people I have known in real life.
also the few times I have discussed 4 hands with semi legit providers, I brought up if they were willing to interact more with the other girl and it was a full on no.
I'm sure the FS places would be open to anything for $$$$