I don't know why people would be surprised. R's all along have seen this as a God given opportunity to gut the ACA, and blame the D's. Why would they want to agree?
Advice: keep up the pressure. The advice comes from 1 Kings 3:22-28. The fake mother was willing to go to the mat and kill the child. The real mother caved in. If not for Solomon (and there is no Solomon here), the fake mother WOULD HAVE THE CHILD BECAUSE SHE WAS WILLING TO HOLD THE LINE. Just saying.
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1 Kings 3:22-28:
22 And the other woman said, Nay; but the living is my son, and the dead is thy son. And this said, No; but the dead is thy son, and the living is my son. Thus they spake before the king.
23 Then said the king, The one saith, This is my son that liveth, and thy son is the dead: and the other saith, Nay; but thy son is the dead, and my son is the living.
24 And the king said, Bring me a sword. And they brought a sword before the king.
25 And the king said, Divide the living child in two, and give half to the one, and half to the other.
26 Then spake the woman whose the living child was unto the king, for her bowels yearned upon her son, and she said, O my lord, give her the living child, and in no wise slay it. But the other said, Let it be neither mine nor thine, but divide it.
27 Then the king answered and said, Give her the living child, and in no wise slay it: she is the mother thereof.