You might not like my war story...but it bears repeating at the git-go:
While your wife and daughter don't have to be "The Trainer", they do need to re-enforce your training rules...otherwise they could undermine a lot of your dog's hard work. For example, it's really unfair to the dog to expect him to understand that he can't jump up on you, but he can jump up on them. What does he do about Grandma? Jump? Not jump? He's going to end up doing whatever he feels like...and he'd be right to do so since he's gotten conflicting rules. Ditto for so many other training situations.
Besides, training is lots of fun for the dog and the person.
While your wife and daughter don't have to be "The Trainer", they do need to re-enforce your training rules...otherwise they could undermine a lot of your dog's hard work. For example, it's really unfair to the dog to expect him to understand that he can't jump up on you, but he can jump up on them. What does he do about Grandma? Jump? Not jump? He's going to end up doing whatever he feels like...and he'd be right to do so since he's gotten conflicting rules. Ditto for so many other training situations.
Besides, training is lots of fun for the dog and the person.