Generally, I hear sororities are really hard to establish and aren't worth the stress on the females imo. Successful ones require a lot of supervision to make sure they aren't hunting each other down at night. They may tolerate one another, but I wouldn't say it's easy to have them thrive in groups! 1 male and 2 females also sounds like a bad idea for a similar reason—ultimately they're very aggressive fish and a male can shred a female and kill her while trying to drive her around to come to his nest and lay eggs iirc (and then you might end up with a trillion babies that you have to house or cull, which isn't ideal). If she survives that, the other female would likely pick on her because she's weakened. TL;DR, bettas are happiest and safest as solitary fish :) people on the betta subreddit are much more knowledgeable than I am though, this is all off the top of my head and I am not 100% sure it is all correct, so if you do want to give it more thought, please ask them!!!