Fellow heirs (4789) (sugkleronomos from sun = with, together, implying a closer relationship, intimacy or union + kleronomos = heir, sharer by lot, a possessor) is a joint heir, one who participates in the same lot. Sugkleronomos speaks of receiving possessions along with another OR OF inheriting together with. Heirs as used by Paul describes one who obtains something assigned to himself with others and the focus is upon receiving an unearned gift. In the biblical sense ‘heirs of God’ are those who receive the blessings that God has for His people. Even in the OT (cf Genesis 12:3) God had included Gentiles in the sphere of salvation, but heretofore it was never on an equal footing with Jewish believers. Now God has revealed that the Gentiles are to share equally with saved Jews as heirs of God, joint heirs with Jesus Christ (Ro 8:17), and fellow heirs with all the redeemed. The two have become one new man in Christ. Kleronomos signifies more than one who inherits, or obtains a portion, it means to take into possession. Sugkleronomos is used of Abraham in Heb 11:9; of a husband and wife who are also united in Christ in 1Pe 3:7; here in Ephesians of Gentiles who believe, as participants in the gospel with Jews who believe, and of all believers as prospective participants with Christ in His glory, as recompense for their participation in His sufferings, Ro 8:17. In Galatians Paul alludes to the equality and heirship of Gentiles writing that... There is neither Jew nor Greek, there is neither slave nor free man, there is neither male nor female; for you are all one in Christ Jesus. And if you belong to Christ, then you are Abraham's offspring, heirs according to promise. (Galatians 3:28-29) Fellow (joint) heirs is used 4 times in the NT... Romans 8:16 The Spirit Himself bears witness with our spirit that we are children of God, 8:17and if children, heirs also, heirs of God and fellow heirs with Christ, if indeed we suffer with Him in order that we may also be glorified with Him. (note) Hebrews 11:9 By faith he lived as an alien in the land of promise, as in a foreign land, dwelling in tents with Isaac (Ge 26:3, 4) and Jacob (Ge 28:3, 4, 48:3, 4), fellow heirs of the same promise;10 for he was looking for the city which has foundations, whose architect and builder is God. (Comment: Isaac and Jacob are co-participants in the promises God initiated with Abraham) 1Peter 3:7 You husbands likewise, live with your wives in an understanding way, as with a weaker vessel, since she is a woman; and grant her honor as a fellow heir of the grace of life, so that your prayers may not be hindered. (note) (Comment: Peter describes believing husbands and wives as united in Christ)