Hi Crimson,
It is still 1inch per gallon as far as adding females I heard that 6, or 9 were good numbers depending on the tank setup. actually I was interested in the sorority dynamic you have in the 'sorority' of less than 5, which you have in the Betta and the one mollie catergory. So, how established are these tank mates?
fin-nippers
ample hiding places for fish 2-3 possibly displacement in the heirarchy
extra quarentine tank for dispalced fish or hospital
and loss of the weaker fish
All these are things you have considered I'm sure but I write for the new and maybe you will find a male to match up your crimson femmes..I swear if you find one at petsmart... as for my boy...he's soo far away! Have you joined IBC?