I think in Steph's case, her long time as support character for Tim and Cass has probably more wight. I think her becoming Batgirl was more a result of her already existing popularity, than the other way around.
Btw. in case of Jean Paul I'm curious if he will really stay around for long. At least at the moment he is pretty far away from the rest of the Batfamily. And the only Batfamily member he was really close to in TEC was Luke, who is also in Limbo.
I'm also wondering what will happen with Huntress, who at least was on the family photo, but has also no book to appear in.