If you want to breed them seriously, you probably want to know which babies have which parents, therefore you need a divider. I don´t think there is any problem with having more than one lady in there. If you only want you guppies to have babies, do you need the hatchery at all? If your tank is well planted, there will be enough babies surviving anyway, unless you have many very hungry other fish in there. You could add some floating plants to give them some more hiding places. The babies will find enough to eat if the tank isn´t brandnew.
Do you plan to sell them? If you want to keep them, you will have more than enough guppies in a short time, without doing anything about it.
