Is Ephraim Fullness of the Gentiles

I have heard Ephraim grieving, 'You have disciplined me, and I was disciplined, like an untrained calf; bring me back that I may be restored, for you are the Lord my God. For after I had turned away, I relented, and after I was instructed, I struck my thigh; I was ashamed, and I was confounded, because I bore the disgrace of my youth.' Is Ephraim my dear son? Is he my darling child? For as often as I speak against him, I do remember him still. Therefore my heart yearns for him; I will surely have mercy on him, declares the Lord. (Jeremiah 31:18-20 ESV)

But his father refused and said, "I know, my son, I know. He also shall become a people, and he also shall be great. Nevertheless, his younger brother shall be greater than he, and his offspring shall become a multitude of nations. (Genesis 48:19 ESV)

Then the remnant of Jacob shall be in the midst of many peoples like dew from the LORD, like showers on the grass, which delay not for a man nor wait for the children of man. And the remnant of Jacob shall be among the nations, in the midst of many peoples, like a lion among the beasts of the forest, like a young lion among the flocks of sheep, which, when it goes through, treads down and tears in pieces, and there is none to deliver. (Micah 5:7-8 ESV)

Lest you be wise in your own sight, I do not want you to be unaware of this mystery, brothers: a partial hardening has come upon Israel, until the fullness of the Gentiles has come in. (Romans 11:25 ESV)

Can multitude of nations be translated as fullness of the Gentiles? In this article "The Two Houses Of Israel - Here a little, there a little - Prophecy" is an interesting discussion on the northern kingdom which I quote with changes to Bible version below:

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When the Lord first spoke through Hosea, the Lord said to Hosea, "Go, take to yourself a wife of whoredom and have children of whoredom, for the land commits great whoredom by forsaking the Lord." So he went and took Gomer, the daughter of Diblaim, and she conceived and bore him a son.

And the Lord said to him, "Call his name Jezreel, for in just a little while I will punish the house of Jehu for the blood of Jezreel, and I will put an end to the kingdom of the house of Israel. And on that day I will break the bow of Israel in the Valley of Jezreel."

She conceived again and bore a daughter. And the Lord said to him, "Call her name No Mercy, for I will no more have mercy on the house of Israel, to forgive them at all. But I will have mercy on the house of Judah, and I will save them by the Lord their God. I will not save them by bow or by sword or by war or by horses or by horsemen."

When she had weaned No Mercy, she conceived and bore a son. And the Lord said, "Call his name Not My People, for you are not my people, and I am not your God." (Hosea 1:2-9 ESV)

Earlier, we read in the Tanakh from the prophetic book of Hosea about how God would punish the House of Israel (Samaria) for their sins.  We saw that Hosea's three children born to him by Gomer were symbolically named to describe the fate of Ephraim:  Jezreel ("God sows") described God's future sowing of the House of Israel throughout all the nations; Lo-Ruhamah ("no mercy") showed that God was not going to have mercy on Israel for a period of time; and Lo-Ammi ("not my people") revealed that those from the House of Israel would not be known as God's people for a time.

But the prophecies from Hosea also show that a time would come when God would regather His children and have mercy on them once again.  Just to set the stage, let's recap a few of the pertinent passages from Hosea that speak of this time of forgiveness:

Yet the number of the children of Israel shall be like the sand of the sea, which cannot be measured or numbered. And in the place where it was said to them, "You are not my people," it shall be said to them, "Children of the living God." (Hosea 1:10 ESV)

And I will betroth you to me forever. I will betroth you to me in righteousness and in justice, in steadfast love and in mercy. I will betroth you to me in faithfulness. And you shall know the Lord. "And in that day I will answer, declares the Lord, I will answer the heavens, and they shall answer the earth, and the earth shall answer the grain, the wine, and the oil, and they shall answer Jezreel, and I will sow her for myself in the land. And I will have mercy on No Mercy, and I will say to Not My People, 'You are my people'; and he shall say, 'You are my God.'" (Hosea 2:19-23 ESV)
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