The first generation of Stryders mentioned in the books are Trev Stryder and his siblings (nicknamed "The Crazies"). Trev Stryder married Linda and had Melanie and Jamie. Magnolia ("Maggie") had Sharon (it is currently unknown whether Magnolia married). It is unknown whether Jebediah ("Jeb") or Guy married or had children. Trev and Linda were erased by Souls and Guy died in a car accident.
Jebediah escaped and founded a rebel cell. He was joined by Magnolia and Sharon and later Melanie and Jamie.
Melanie partnered with Jared Howe and Sharon partnered with Eustace ("Doc").
Wanderer and Ian are worth mentioning, because Ian is partnered to Wanderer ("Wanda") and Wanderer's relationship to Melanie and Jamie is that of siblings (thus making her an adoptive member of the second generation).