Jacob's great grandfathers name is Ephraim Black, was the last Quileute chief and was in the "last" wolf pack.
Quillete Tribe
Rachel and in case you were wondering, Paul imprints her.
Because he was in an accident.
Jacobs tribe is called the Quileuet tribe which is made from 4 families;AtearaBlackClearwaterand Uley.
I'm pretty sure that it never says, but you find out in Breaking Dawn, the only time that she's mentioned, that she died in a car crash.
I think it is Jacobs sister Rachel.
Billy Jacobs's birth name is Paul Jacobs.
Jaye Jacobs's birth name is Emma Jacobs.
Jacobs dad
Al Jacobs's birth name is Albert T. Jacobs.
Catherine Jacobs's birth name is Catherine Renee Jacobs.
Devery Jacobs's birth name is Kawennhere Devery Jacobs.