I know an Augustus who wears the name well, I'd consider Augustine usable. With Hugo, I think people are more likely to think of the recent movie than Hugo Chavez. And Hugo John sounds fine to me.
They're all great choices, but Augustine John Isaac is my favorite.
Wish Augustine were August. That would definitely be my pick!. As it is, I think you are going to have prn issue. People with say
Aw gus teen.
I think Hugo and Gabriel go the best with your sibset, though I like Augustine.
I like Hugo better, but I don't know about using a mn as a first all the time.
I guess that would be my choice
I picked Gabriel because I think it works best with Julian, Bethany, and Theodore. Hugo is a little too short and Augustine is a little too long. While I like Gabriel Isaac, I don't like Guy to much with it unless it's a family name. What about one of these instead:
Gabriel Isaac John
Gabriel John Isaac
Gabriel John Hugo
Gabriel Isaac Hugh
Gabriel Hugh Isaac
Guy is a family name, but so is Isaac. I think that we are leaning towards Gabriel John Isaac.
I was just saying in another thread that Gabriel is my favorite G name ever for a boy. It's actually one of my favorite names for a boy period. So that's my first vote, although I really love the John Hugo Isaac combo. Love it's flow and I adore Hugo!