Deuteronomy 23:3 . "An Ammonite or Moabite shall not enter the assembly of the Lord; even to the tenth generation none of his descendants shall enter the assembly of the Lord forever."
...thy people shall be my people, and thy God my God...
With that statement (and her marriage to a Jewish husband) she was no longer an Ammonite or Moabite but a Jew.
If illegals did the same, they'd find a much better reception on this forum.