awww they are adorable. I should get some pictures of my 5 girls on here. They are in a 10 gallon tank with lots of plants, they love it. Although I dunno if I could get pictures as clear as yours. Those are awesome pics.
Well it depends on the betta. Sassy I got last year and shes in with the 4 others. They had a tiny fight but have worked it all out thankfully. I think it was mostly Sassy wanting to be boss fish. Shes really big for a female betta. But if you feel its not safe then maybe you shouldnt, its up to you. But they are really adorable girls.