I think it would cruel and inhumane to force these dogs to live outside!
At the age of 7 your female is considered a senior for this breed...and with arthritis she would not be comfortable. Does not matter how nice a dwelling you have built.
Rottweilers are people dogs...they love to be with their family, and share their life with you. Now you have a baby and another on the way...and boyfriend wants them out of the house???
Not only would they be unhappy living outside...they will in all probabilty start barking and become protective of their yard....and become annoying to neighbours.
Keep them inside, with their family. Can you baby gate an area for them...so that they are not underfoot?
Gina