I have some papers from Tuscarawas Co. OH re Frederick Knestrick: Case No. A, Nov. 1811 - will admitted to Probate and letters issued to John Knestrick and Richard Burrel. Richard was the husband of Margaret Knestrick, daughter of Frederick, I believe. (P. 2 Administration Docket 123, Tuscarawas Co. OH; LDS film 0890338). I have his will.
Henry Knestrick also died in Tuscarawas Co. OH and on Sept. 29, 1849 letters of administration were granted and sureties to Jonas Kohr, Daniel Ziegler. Appraisers Hugh Goranch, John Forney and George Welty. Administrator was John A. Keplinger (Case A 1089, Tuscarawas Co. Administration Docket 123 p. 349. LDS film 0890338)
My John's estate was filed Case A1095, Nove. 23, 1849 (quite a few members of this family died in 1849) and I have his will. (same LDS film)
On Ancestry.com I found in Maryland Marriages 1655 - 1850 my John and Sarah plus Willliam Kenestrick married to Polly Younce 22 Jan 1811 also in Washington Co.
This family was also in Washington Co. PA. I have copies of p. 10 and 11 of the Keyhole Vol. X NO. 1, Jan. 1982: Knestrick Family of Washington County, PA. It indicates that John Knestrick landed in Philadelphia Sept. 26, 1741 coming from a German-speaking country. It was he that died in Washington Co. MD in the fall of 1784. Children were Catherine m1. Chaney, m2 Dutwiler, Frederick, Henry, John, Magdalena m. Henry Elder. The son Henry's descendants follows. Sounds like what you have.
I will look up what I can next week when we go to the Allen Co. Public Library in Ft. Wayne, IN.