I recently reviewed the 1773 tax records for Baltimore County and found the following Parrishes listed. You'll note that there are quite clearly two Joseph's. Most likely, one is the Joseph Parrish born in 1724, son of William (1678-1771) & Susannah who married Cassandra Talbott. My guess is the other is his nephew, and likely the man who married Charity Bosley in 1768.
It's worth noting Pipe Creek Hundred was located approximately in current day Carroll County and abutted Piney Creek Hundred (where Joshua's wife Barbara Timble lived).
Middle River Upper Hundred
-Edward Parish (listed in a way that makes him seem like a single freeman)
-Amon Price (possible brother of Merryman?)
Mine Run Hundred
---Nicholas Parrish (under Will)
-John Parish (same as above? different page)
Patapsco Lower Hundred
-Aberilah Merryman, widow
----William Ginkins (listed w/William Parrish)
2nd page, Pipecreek (different writing style)
-William Galbraith (any relation to Robert in Shirley twp, PA?)