[Jan_Sobieski]

New Covenant is between Yahweh/God and the whole nation of Israel. Those who partake of this New Covenant are those Israelites who are in Christ.

So we Gentiles are grafted into Believing Israel and believing Judah and get to partake of this “New Covenant”?

[DSH]

So we Gentiles are grafted into Believing Israel and believing Judah and get to partake of this “New Covenant”?

Yes. That's how I read the Apostle Paul. In Romans 9-11, and, of course, Galatians 3:

"Know then that it is those of faith who are the sons of Abraham. And the Scripture, foreseeing that God would justify the Gentiles by faith, preached the gospel beforehand to Abraham, saying, In you shall all the nations be blessed.' So then, those who are of faith are blessed along with Abraham, the man of faith."

-- Galatians 3:7-9. I'm not sure how Paul could have put it any clearer. Nevertheless, over the many decades, starting early in the 19th century, the "dual covenant" proponents have gone out of their way, it seems to me, to miss the point.

[Cronos]

we gentiles are grafted into Israel - Israel is no longer just the genetic descendants of Abraham, but his spiritual descendants

[Philsworld]

So we Gentiles are grafted into Believing Israel and believing Judah and get to partake of this “New Covenant”?

Correct