I am not a member of Fetlife so can't speak to that organization. But I am in Swing Lifestyle (SLS) which has given me many wonderful carnal experiences. I have gone to many house parties where you can either pair up with another lady, couple or have a 3-some, 4-some or more. I have had a couple of orgies at these functions. Last Fall, I went on an SLS weeklong cruise to the Caribbean. I took a Provider who also happens to be a swinger and we had lots of fun, every day, several times a day!
https://eccie.net/showthread.php?t=3069742
Additionally, there are many swinger resorts in Florida where orgies can happen.
About 7 years ago, a Jacksonville Provider organized an orgy which can be read here:
https://eccie.net/showthread.php?t=2538518
I occasionally see in the forums about someone trying to organize a gang bang or an orgy. Keep your eyes open!
Good Luck & Have Fun!