The logistics of an orgy can be challenging to say the least. It's tough enough just getting a doubles session scheduled. Coordinating a date, time and place for 12-14 people to be naked in the same room for a few hours is probably akin to herding cats and then getting them to mate.
There is a hobbyist that coordinates group sessions in Austin and Houston with UTR ladies.
Slave Guinevere managed to coordinate and pull off 3 legendary orgies from March-May 2014 with the top ladies in SATX.
https://www.eccie.net/showthread.php?t=997714
https://www.eccie.net/showthread.php?t=1026243
https://www.eccie.net/showthread.php?t=1056245
They had monitors that watched and made sure the boys played safe when moving from one lady to another. The monitors were rewarded in the end with a BNG from the ladies.
With 4-5 ladies playing, I imagine the rules would have to be the same for everyone. It would be too much of a pain in the ass to remember which lady allows Greek or CIM, and which doesn't. That being said, it definitely sounds like a lot of fun!