I keep three females and a VERY EASY-GOING male Betta in a ten gallon.
Originally there were some nipped fins, but now everything is prefectly fine.
But, I watched them for the longest time during the first week just to make sure.
Now they get along fine...
It isn't uncommon, espiecally during feeding, that they'll gather around the front of the tank. Swimming together.
It is kind of cute, when one of the females swims beside the male trying to get my attention. Sometimes they are swimming all over each other trying to get the food [LOVE, their bloodworms].
BUT!!!!! I advise for the benefit of your fish, keep a very careful eye on them.
Originally I had another group of Bettas, which I had to give away cause I wanted to breed some guppy-tailed Mollies.
This first group were NASTY. No matter how many plants there were, or how many females [five in total] they'd pick on each other. The male was so nutty I had to give him back to the petstore about an hour after I had got him home.