Marguerite Jacqueline Cullen is the biological child of Carlisle Cullen from his human years, and has since been turned into a vampire.  They are reunited during the events of Eclipse, and she finds out that he now has a new wife and adoptive children. 

Your OC is friends with her, and he/she wishes to become a family member to the Cullens.  Marguerite meets her mate, Embry Call, a shapeshifter from La Push, on the Quileute Reservation.  Now, Embry is a part of the Cullen family by the Imprint bond he has with Marguerite.  So is __________, your Imprint or Mate.