do you have them on censuses? did they stay in Hempfield Township?
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I'm just going to throw some references for Westmoreland County at you that might help. A lot of them might be online somewhere by now.
Della Reagan Fischer, copier and compiler, Marriage and Death Notices
from Weekly Newspapers, 1818 - 1865, Westmoreland County, Pennsylvania, Volume 1 (McKeesport, Penna., typescript, 1963).
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Agnes Campbell Tomichek, Marriage and Death Notices from Newspapers, 1808 - 1921, not all inclusive, Westmoreland County, PA. Compiled and typed by Mary Jane Mains. Greensburg, PA: Westmoreland County Historical Society, 1988.
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Mary Jane Mains, compiler, Newspaper Accounts of Births, Marriages and Deaths, 1808-1929 (not all inclusive), Westmoreland County, Pennsylvania (Greensburg: Westmoreland County Historical Society, 1994).
lots of overlap in those three books, if I remember right. Mains was more complete, but didn't have my gg grandmother's marriage, which the other two did.
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Index to Wills of Westmoreland Co., PA
Vol. 1-9, 1773-1896, compiled and published by Clossin of Apollo, PA
"As recorded in Will Books I-IX, of the County Courthouse"
the wills are indexed somewhere on line, maybe ancestry or maybe the county site itself. I know I saw them somewhere recently. So no need to find that book.
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here's another one that has probably been put online by now:
Tax Lists, Westmoreland County, PA, 1786- 1810, edited by William Dumont (Washington, D.C.,: National Genealogical Society, Special Publication No. 33, 1968)
tax lists fill in the years between censuses. If someone, maybe a grown son, disappears between censuses, the tax lists might help you figure out when he left the area.
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this is probably at archive.org. find it free, it is long since out of copyright in the US and should be there or maybe google books.
History of the County of Westmoreland, Pa., with Biographical Sketches, etc., edited by G. D. Albert (Philadelphia: Everts & Co., 1882)
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just found these, haven't looked through them. keep for future reference
https://www.germanroots.com/penngermans.htmlhttps://www.germanroots.com/index.html----
Pennsylvania German pioneers; a publication of the original lists of arrivals in the port of Philadelphia from 1727 to 1808
https://archive.org/details/pennsylvaniagerm42straThere is another transcription of the baptism records: Paul Miller Ruff's German Church Records, Westmoreland Co., Pennsylvania
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if you don't find the family by searching the passenger lists at familysearch.org or ancestry.com, try here. It is a little harder to work with, but it had my German ancestor's arrival in Phila.
https://immigrantships.net/They could easily have arrived in Philadelphia, or possibly Baltimore, if there destination was Westmoreland Co. Not everyone arrived in New York.
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based on their birth years, both Christian and his wife could have been born in America. You might need to find their parents before looking for arrivals. Can you find Rose or Boyer families in the area? If not, try farther east in Pennsylvania, since the general migration was east to west.
There's a good chance they were Palatine Germans, lots of them in Pa. and they were fleeing in the mid 1700's . SW Germany, if I remember right.
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If you run into Jacob, Joseph, or John Kern, that's us. Joseph was my ancestor, the other two were brothers. John was in Hempfield Twp, I'm pretty sure. Joseph was in town, I think. All three were born in York, York County, Pa, to Jacob Kern who was the immigrant. Same time frame as your Christian, so that is why I'm guessing he was born in the US, not Germany.
