Claim. The grandfather in a household represents God and the spirit-world as a special envoy of heaven; attending grandparents like God is the family-scale practice through which the four-position-foundation is realized.
Elaboration. SMM gives the grandfather a precise theological position: “The grandfather symbolizes the past. The subject partner of the past ages is heaven, the spirit world. The grandfather can be called the representative who connects the spirit world with the earth. He is God’s ambassador who connects God and all the good things in heaven to his family on earth” (4.6. Entering heaven as a family unit, 249-304, 1993.10.11). Three-generation structure carries cosmic significance: “The grandparents stand in the position of the king and queen of heaven. The father and mother are the king and queen representing the families of this world. Their descendants … inherit the union of these two kingships” (ibid, 246-74, 1993.3.23). The practice is concrete: “You should attend your grandfather like God, and your father and mother like the parents who can unify the world” (ibid, 249-265, 1993.10.10). This grounds inter-generational filial piety in cosmology, not custom — household reverence is the local realization of the kingdom.
See also. csg-heaven-entered-only-as-royal-family-with-true-love