Do you have a garage or other outbuilding and a dog crate? If you are serious about a quarintine then he should not be allowed to range anywhere the girls already have access too. so you willl be in isolation for 3 weeks or so. After that I agree with golddogsmom. If they are all ranging then there is less confrontation and more room to retreat if neccessary. Generally introducing animals of the opposite sex is a lot easier than introducing same sex animals in my experience.