Here is more information on this topic courtesy of this article by Mr. Ken Raines. (Bolding mine.)
On theology, [Nelson Barbour, an early and important influence upon C. T. Russell,] taught in the book [Three Worlds and The Harvest of This World (1877)], as Russell would later in The Watch Tower, that the Church and Jesus together constituted The Christ (pp. 5-6). Jesus and His bride, the Church, constituted the "Second Adam and Eve" (p. 11). The church will become Gods, in fact, they would "become part of the Godhead" (p. 13)... These 144,000 "spiritual beings" would "materialize" as men on earth at will during their Millennial reign...thereby keeping tabs on the spiritual development of mankind during this period (pp. 43 47). Mankind's worship would in part consist of serving and obeying these "rulers" or "instructors" in the Millennium (p. 68).
So not only did the Mormons teach this God Family doctrine but also the early Watch Tower Society. Maybe HWA actually stole this idea from the Watchtower Society.