You can't "further define" Natural law through a man made act. You can only recognize it, not modify it.
It is like saying that congress can pass a law granting citizenship to anyone born of Chinese Parents (which they theoretically can, but which would be politically impossible) is a "natural born citizen", but it would not make it true.
"Natural born citizen" cannot be re-defined by the whim of congress. God help us if the meaning of Constitutional terms could be re-defined according to the whim of Congress.
We are already seeing Judges attempting to do this, but we always knew that Judges are mini-Tyrants.
Writing the Constitution, adopting the Constitution, amending the Constitution and interpreting the Constitution were/are all “man-made acts.”
All statutory law, treaties, case law, and federal regulations that haven’t been explicitedly ruled to be unconstituional exist under the Constitution. That includes recognizing who is and who is not a natural born citizen.