John McCroskey & Margaret DUFF of VA/SC/?

Would like to locate information on the above family.Margaret Duff and John McCroskey were in Pendleton Dst. SC in the early 1800s..may have travelled to S.W. Kentucky with Agnes Carson Duff, widow of James DUFF, and sons, Samuel C., James Jr., dau. Nancy, and others.Margaret Duff was the daughter of James and Agnes Carson Duff- mentioned in James Will as well as her husband John McCroskey.Appreciate any info on these families.They may have moved into N.E. Texas in about 1820-30 time period. Will share what I have so far.Thanks. B. Smith