The place to find land records is in the Delaware Archives in Dover.
Abstracts have been published for that time period for Deeds Books M, N, O (not P, Q, R, S) and a few subsequent volumes into the 1820s -- but those by Neil and Leslie Keddie (the later ones) are out of print and will not be reprinted.
You can locate the abstracts that are in print with a web search.
You would want also carefully to scrutinize the Orphans Court records; abstracts for those up to 1776 have been published by Skinner, and a series of CDs available from the Delaware Genealogical Society cover up to 1797.There are no abstracts available for after that date, the records are in the DE Archives.
People living along the NW Fork often moved back and forth to/from Dorchester County, MD and Kent Co, DE, more places to look in both census enumerations and other records.