
I am sure Westie lovers on this board will advise specifics. If you enjoy and are happy with owning bitches have another bitch. I own several generations of bitches with no problems.
A friend who has just got a puppy bitch to keep her Male dobe company, as her two oldies won't last much longer, has had trouble with them getting on, as the pup is very pushy, and the male has always been very soft, so he looses his rag with her. If he was generally more forceful, she wouldn't be taking such liberties, which she doesn't with the old girls!
The coice as they say, is yours (bearing in mind that if you have an entire bitch, it is best to have one or other neutered if you get a male).