The quit-rent agreement for Peter, Margaret and Nicholas states as follows:
"Frederick County, Maryland. State of His Lordship's Manor of Monocacy. Monocacy, 1767, No. 65. Leased Sept. 29, 1759 to Peter Hertzog, 100 acres; Margaret Hertzog, tenant in possession; annual rent, 0-10-0; alienation fine, 1-0-0, leased on lives of Margaret Hertzog, age 55, and Nicholas Hertzog, age 32."
The date of the agreement is 1767. Were the ages based on that date instead of the original lease date? If so that means Margaret was born circa 1714 and Nicholas circa 1735. This would more closely coincide with the dates given by Mary Mae Hartsough and the date of birth given by Lawrence Leonard in his history of the Koontz/Kuntz family (13 Nov 1712, Middleton Parish, Ireland or Somerset County, New Jersey).
The Archives of New Jersey documents a will for Nicholas Kones that shows a Margaret Harsough as his daughter.
"1746, May 29 - Kones, Nicholas of the Mountains of Somerset County, Will of.
Sons - Jacob (oldest), Michael (sole exr., and heir of all land he now lived on, etc.), and Adam.
Daus - Barba Menton, Margaret Harsough Elizabeth Ranger Mary Harpending"
A Nichol Kuntz is shown as a neighbor of Peter Herzog in the Janeway books.
I think there is a good possibility that Peter had two wives with very similar names. One (Anna Maria Margarita Schmidlen) may have been born circa 1704 and married to Peter in Germany, the other (Anna Margaretha Kones) born circa 1712in Ireland or New Jersey.
The statement about woman having children at 45 may not be relevant if this is the case.