The problem is that a lot of people think the people of Israel are forgotten by God. In no way are they forgotten.
Paul said in Romans 11:1 I ask then, did God reject his people? May it never be! For I also am an Israelite, a descendant of Abraham, of the tribe of Benjamin.
Of course they are not forgotten. All of Israel is being dealt with. It was declared by God through the Prophets. In Romans 9,10, & 11 Paul is citing alot of scripture here. The scripture Paul is citing clarifies the context of what Paul is talking about. Paul references Hosea specifically chapters 1 & 2, He also cites Isaiah, Moses, Ezekial, Kings, Jeremiah, Joel, Psalms. Paul is also teaching how to study scripture, the importance of understanding scripture, how scripture defines scripture and pointing to the fulfillment of God's plan by compelling his audience to read & study the scriptures credited to Moses & the Prophets.
Paul is teaching a mystery that is revealed and proven by the study of scripture.
The scriptures show Paul is talking about the curse & promised restoration of the two kingdoms, "all of Israel". Paul declares he is a Benjamite, one of the tribes of "all of Isreal". Why the salvation by the "election of grace" for "all of Israel" is connected to the "fullness of the gentiles".
Paul knew where Judah, Benjamin, partial Levi, the Jews, the kingdom of Judah, the remant of 7000 spoken of in Isaiah, was. Paul also knew where Epharaim & Mannasseh(Joseph), Rueben, Simeon, Zebulun, Issachar, Dan, Gad, Asher, Naphtali, remaining Levi, the kingdom of Israel were as well. They had been cursed, cut off, scattered among the nations, the ethnos, the gentiles for a purpose. God promised to redeem them and that they would be called by a new name, "sons of God".
This is why their curse has become a blessing to the gentiles, the ethnos, the nations. The rest of Israel (Epharaim & Mannasseh(Joseph), Rueben, Simeon, Zebulun, Issachar, Dan, Gad, Asher, Naphtali, remaing Levi), is among the ethnos, the natons, the gentiles. As the gentiles, the ethnos, the nations recieve Christ ,the"gospel of grace", so does "all of Israel". Their curse & promised redemption becomes the blessing of the entire world through Christ!