Will my new cats ever be accepting

Will my new cats ever be accepting

I have 2 female cats, ages 1 and 2. I recently took in a baby boy stray around 4 months. The girls are not happy about this new addition. They hiss, and are upset about the new boy. I thought that female/ male relationships were friendly. I would like to know if anyone has had a similar situation? If so how did it work out?