ZooBabyBlog has sixty posts (and counting) covering the baby gorillas born last year at the North Carolina Zoo, and their family interactions, etc. If you want to know anything about silverback Nkosi, mothers Jamani and Olympia, their boys Apollo and Bomassa; and Acacia (expecting summer of 2013), you might find the information covered in one of the posts found at Baby Gorillas Bomassa and Apollo Grow Up
That's a nice article. They got the name wrong though. That's Baby Apollo, not Baby Bomassa pictured there.
Im sure once the impeding arrival is born and is a little older they will seek a new male. They probably wouldnt want to risk the new arrival with a male who might be inclined to kill it in order to sire his own offspring with the mother. But then again I could be wrong in the case of a new dominant male gorilla.
Construction begins this month to renovate and expand the gorilla habitat. Three more apes will be coming from Henry Doorly Zoo as well. NC Zoo to debut bigger gorilla exhibit :: WRAL.com
Babies aren't safe with a strange silverback which is not their father, until they are at least three or even four years old. Even then they can be subject to attacks, sometimes the new silverback will still try and oust them from his new group if they are too big for him to kill, as genetically they have no value to him. No set rule though as other times they will be accepted without trouble.