I have breed Bettas before with great results but I personally never looked up or thought about asking if the female bettas can be placed in a tank with other female bettas. Males I know that is a HUGE no-no.
And the other question is provided I remember right I can place a betta in a tank with Swordtails? It's been about 6 or more years since I have done the whole fish tank ordeal. If that is possible I was planning on picking up another male from my local fish store since they got a nice shipment in today I found out.