The Minor-Races and Empire Independent planets, (brokeoff, lack of communication forming colony into independent Soverign state, etc.) Should have a set of Diplomatic options of their own for players and Artifical-Intelligence which is a Major Civilization. To begin with, These small flourishing, (Or dying) civilizations and Independent Empire populations are politicaly, economicaly, militarily and technologically inferior unless their Empire has brought unto their planets many facilites, research, etc.
Thus Civilizations, Major only, have the capacity to conduct with them "Annexing" or "puppeting" actions. For Example a Colony of the Drengin-Empire broke off due to lack of support with their PlanetClass-9 planet. Fortunanely they look to the Human-Empire for Trade and military support due to the dying relationship between Humanity and Drengin. You have in the negotations convinced the Drengin Independents to become a state, joining Humanity politicaly closer and establishing both as a "Commonwealth", bringing about many advantage and disadvantages to culture, economy to both groups and relationships.
How about it? it would satisfy many fans of Galactic Civilizations craving for a more indepth Diplomatic engine in GalCiv2.