I have normally only kept male betta but after reading about the females I decided to get some.
The lady that helped me in my LFS said the females get on better in groups of 3 or larger. so I got 3, a white one, a double tail and what appeared to be a plakat. (They were all in the same tank in the shop)
They were put into a 10g tank of their own. They got on fine for a day or two but then started fighting. The plakat who was the smallest of them relentlessly bullied the other 2 until one if them just gave up and I came home from work to find the white one dead :(
I separated them, the DT is now in the 10g with 4 cory and the plakat is in a 5g of her own (I think she's too aggressive for company) they've been in their new homes a couple of weeks now and seem to be getting on really well.
I've done a lot of research on this and all the information I get back is so conflicting, some say you can keep females in groups of three, some say it has to be a min of 5.
I'd be interested to hear if anyone has had success with keeping them together.