The Elizabeth you mention who died in 1823 in Green Co, KY was Elizabeth Wise, who as the widow of William Newton of St Mary's Co, MD married in 1796 to Ignatius Brown.
She was the sister-in-law of the Ignatius Newton who died in 1812 in Washington Co, KY.
She was the mother of the Ignatius Newton who died in 1841 in Green Co, KY.

If you have any documentation to the statement that John Norman Newton was the son of Ignatius I would greatly appreciate.