In Breaking Dawn, Jacob imprints on Renesmee, which means that he falls in love with her, committing fully to being her protector, and later when she is grown, her partner. This aspect of the novel has made it controversial, understandably. Jacob is seventeen or so years older than Renesmee, but he will cease aging as long as he is a werewolf, and when Renesmee ages to a certain year, she will stop aging as well, so the match will work. If Renesmee and Jacob marry, which is very probable, then yes, Jacob would become Bella and Edward's son-in-law. Strange, I know.

this is true because jacob falls in love with Renesme. it all depends on how old edward was when he was turned into a vampire if bella's duaghter grows up or not. plus werewolves don't really age either so it all depends on the life cycles of both vampires and werewolves xoxo

No they are not related in a such a way. However Jacob did imprint, a type of werewolf instinct that makes you have a deep feeling of protection and love towards another one that could be a long life partner, on Nessie. Even though Renesme is very smart she is still only a couple of months old remember that. Although Jacob is going to be by Nessie's side 24/7 if he can, it's going to take Edward sometime to even warm up to the idea of marriage between his daughter and friend-enemy.

Well not exactly but Bella and Edward have a child and this is the child that Jacob imprints on. Neither of the parents are happy about this fact nor want to accept it but as time goes on they know he just wants to keep her safe and happy. Since Jacob will stop aging he wants to wait for her

Not technically. That can't happen because bella and jacob aren't related in any way. But, in breaking dawn bella and edward have a daughter, called Renesmee, jacob imprints on renesmee as soon as he sees her. Edward isn't happy about this, and neither is bella in the beginning. But she comes to realise that all jacob wants for renesmee is the same that she wants so she calms down and accepts it.

At the end of the book the volturi come because Irina, one of five vampires that think of themselves as the cullens' entended family, sees bella and renesmee one day in the forest and thinks it is an immortal child (these are illegal creations because they are too young to undertsand their limitations and couldn expose the secracy of vampires all together). Alice and Jasper leave without telling them anything because Alice knows that aro, the leader of the volturi, wants to take her and use her skill.

Bella decides, using alice's clues that she left, that the only safe thing to do for renesmee is get jacob to run away with her. When the volturi form a discussion amongst themselves bella tells them about the plan and edward understands immediately. Bellla thinks it's too risky and that they will probably all die, she can't let that happen to renesmee. She hugs her tight, passes her to edward and he puts her on jacob's back (he's a wolf at this point). Edward puts his head on the shoulder of jacobs he has just put renesmee and says, 'goodbye jacob, my brother...my son'. But of course, he doesn't mean this literally.