Morrison's Batman and Son arc, and the Resurrection of Ra's Al Ghul both set up the adopted child versus the genetic child story element. And now in GM's Batman and Robin, Bruce's relationship to Dick, Tim and Jason is being downplayed. The important thing to GM in this title is that Damian is the one true son. Dick is not a son. He's not even a ward, so that word's wrong, too. Even if he'd never been adopted (which he was) he couldn't be a ward at his age.
This story, in Batman and Robin, is not the story of two sons of Batman. It's the story of one son and one other guy. Which is not accurate and is a significant change in canon. It's not a single story detail that GM is forgetting. He's remaking the basics when he ignores the father son dynamic between Bruce and Dick. Or Tim or Jason, for that matter.
Dick, Alfred, Bruce, Tim and Jason do not regularly use the words 'father', 'son', or 'dad' to refer to each other. But they do use those words sometimes. At other times, the relationship still exists, even if those specific words aren't being used. (Unless the relationship is being ignored in favor of Damian being the only one. And the only place I'm seeing that happen right now is in B and R. I'm still getting a sense of family from the other Batbooks.)
Here are some more past father and son moments from canon and a variety of Batwriters:
And in Batman and Robin, Dick is not being depicted as a son. Damian, we are reminded at every turn, is. This idea, of the story being about one real son and one family friend, also jives with GM's own personal take on Bruce, which is that Bruce and Dick were pals, not father and son.
Personally, I'm not caring for it. I think I'd like it more if there was more focus on characterization instead of how B & R are such cool and clever crimefighters.