Amulon has their wives plead for them. We have seen this tactic before in the story of the people of Noah who fled before the Lamanites. When the men who refused to abandon their wives and children turned to face the Lamanite army, they also had the women plead for them (Mosiah 19:13).
While it is true that the Amulonite women were the "daughters of the Lamanites" it is probable that we are seeing in this action a fairly standard mode of negotiating surrender.
In the current case, it might have been the Lamanite heritage of the women that could have been helpful, but we must remember that it would be a tremendous coincidence if any of the immediate family of these women were in the current Lamanite army. We might expect that the tremendous coincidence of such an occurrence would have warranted a comment that brothers found lost sisters, or cousins found cousins.
We do not get that, only that the women stood forth to plead for their now-husbands.
As a final note to this incident, we note that the women were willing to plead for their husbands. We must remember that these are women who had been forcibly kidnapped. Why would they plead for the priests of Noah? Why wouldn't they condemn them and have the Lamanites kill them instantly?
Once again, we do not know. We may suppose that some time had passed, and either they women had grown to care for the husbands, or perhaps there was sufficient time that they had children, and that the family bond had been created. Since the priests of Noah were well educated, it is not inconceivable that they were quite convincing in their descriptions of the reasons why the women would want to stay with them, rather than run away in the night.