For the worse!! Never mix a male with females except for spawning. Also, there are going to be enough aggression issues in your tank without adding to the problem.
I agree with everything pipoodle has said, you cannot keep bettas in that set-up not male or female.
NEVER mix sexes unless spawning and as has been said even then they are watched closely as one will kill the other in minuits, i seriousely recommend you return the fish.