That the gentiles should be fellow-heirs with each other?
the "both" made "one"/ the "twain" made "one new man"!
1.The Jews and Greeks, those gathered during Paul's Acts ministry, those in the commonwealth of Israel. They had a hope (Genesis 12:3 KJV). They are the "them that were nigh" (Ephesians 2:17 KJV). They were aligned with Israel. They were in the promise: heirs according to the promise (Galatians 3:29 KJV).
...And
2. The "you Gentiles", in time past aliens from the commonwealth of Israel and strangers from the covenants of promise, having no hope and without God in the world (Ephesians 2:11-12 KJV)
Ephesians 2:13-15 KJV But now in Christ Jesus ye who sometimes were far off are made nigh by the blood of Christ. 14 For he is our peace, who hath made both one, and hath broken down the middle wall of partition between us; 15 Having abolished in his flesh the enmity, even the law of commandments contained in ordinances; for to make in himself of twain one new man, so making peace;
We (as and of the 2. group above) are fellowheirs, and of the same body, and partakers of His promise in Christ (Ephesians 1:12 KJV beginning with Paul 1 Timothy 1:16 KJV which includes the Romans, Corinthians, Galatians and Thessalonians) and partakers of His promise in Christ by the gospel:
Ephesians 3:6 KJV That the Gentiles should be fellowheirs, and of the same body, and partakers of his promise in Christ by the gospel:
(by the gospel: 1 Corinthians 15:1-4 KJV)