You can buy more chicks from a local breeder, mail order through a hatchery, or buy chicks from a farm store. You can purchase started pullets through some places, but they are far more expensive than chicks. Some people occasionally rehome entire flocks for whatever reason, but sometimes it's because they're past laying age.
The usual rooster to hen ration is 1:10, otherwise the rooster will stress the hens and cause things like broken feathers or even a bare back. If you want to keep both roosters, you will need at least 20 hens. If you only want 2 hens, it might be best to keep them without a rooster. They do not need a rooster to lay eggs. Unless you have a particularly laid back and docile rooster, I think those 2 hens will quickly become stressed and start having bare backs and other injuries from the rooster doing his duty.
