I'm amazed that there is no fighting. It might not be a lasting harmony, especially since....
Your girls are filling up with eggs! No worries. However, they may become more agressive to one another or the male now since they will be competing for mating rights.
I don't know what type of bettas you have or if you are intending to breed, but I'm assuming you do not intend to, so if you see the male bubblenesting, you can either remove the girlies to prevent an accidental spawn, or let them have at it then destroy the nest and dispose of the eggs promptly.
edit: just in case you read this and consider breeding, please read the thread on proper breeding; if they are VTs, it shouldn't be done at all, both genders will need prepping, the offspring can # in the hundreds and be hard to place, etc.