Isaiah Harrison was married twice. His first wife was Elizabeth Wright (daughter of Gideon Wright and Elizabeth Townsend) and they married about 1688, their oldest child Isaiah Jr arriving in 1689. After Isaiah Jr, other children were born to this marriage, viz. John (1691), Gideon (1694), Mary (1696) (m. Robert Cravens), and Elizabeth (1698).
Following the fifth child's birth, Isaiah's wife Elizabeth passed away. Soon thereafter he married again, to Abigail Smith. While the children of Isaiah's first wife are clearly documented with birth dates, in the town records of Long Island, NY, we are not so lucky with the fruit of the second marriage, other than the fact that those children started arriving about 1701, with Daniel. Following Daniel, was Joseph (1702-04), then Thomas (1704-05), then Jeremiah (ca. 1707; m. Elizabeth Patterson), then Abigail (ca. 1710; m. Alexander Herring), and also Lydia (ca. 1706; m. Samuel Stewart), and lastly Samuel (1712-13). There may have been other children, but these are the ones we know of.
As for my Margaret Harrison, she was born circa 1740/45. Therefore, she could have been a daughter of any of the sons from the second marriage of Isaiah, but not a granddaughter. Likewise, she could have been a granddaughter of any of the sons of Isaiah by his first wife, but not a daughter. Enough is known of each branch of the family to arrive at those conclusions with confidence.
Looking closer at the sons of Isaiah, we can quickly rule out Isaiah Jr, John, Daniel, Thomas, and Jeremiah, as either fathers or grandfathers of Margaret Harrison Patterson (MHP).
Isaiah Jr may have lived in Salem Co., NJ for a period of time, but nothing has ever been known of him in either DE or VA. Nor has that name shown up in any of the families of MHP (or her presumed siblings). Isaiah Jr. may have died young, but nothing is certain in his case.
On the other hand, sons John, Daniel, Thomas, and Jeremiah are "fairly" well documented. There are holes in each branch, but there seems to be enough evidence to rule them out as potential fathers, or grandfather, in the case of John.
That leaves Gideon (as a grandfather) and Joseph and Samuel (as fathers), as our remaining possibilities. I used to lean heavily toward Joseph as a possibility, but his presumed family seems to be fairly well delineated as that which migrated with the Samuel Stewart clan (S.S. married Lydia Harrison, daughter of Isaiah Sr.) to the Yadkin Valley of NC in the late 1740's and 50's. Furthermore, the Harrison bunch that moved with my Pattersons to the Kings Mountain region of SC didn't move there until the early to mid 1760's. Again, Joseph's branch just doesn't seem to fit well.
Thomas Patterson, who married Margaret Harrison on 24 Dec 1761 in Augusta Co., VA at the Peaked Mountain Church near Harrisonburg, named their oldest son, John Patterson. He is my ancestor. There do not appear to be any Johns in the Patterson bunch prior to this, so it seems the name "John" had to come from the Harrison side of the family. But again, Margaret does not appear to be the daughter or granddaughter of John Harrison, Sr. And John Sr's son John Jr, who was murdered in 1763, never married nor had any children. So again, it seems to rule out the John Harrison branch of Isaiah's clan. Thomas Patterson's parents were Robert and Sarah Patterson. Robert's sister was the Elizabeth who married Jeremiah Harrison.
And then there were two
So that narrows it down to two branches of the Isaiah Harrison clan. Gideon and Samuel. Hardly anything is laid out plainly for either of these sons of Isaiah. I'll come back to Gideon later. As for Samuel, he was the youngest known son of Isaiah. Even that fact, that he is a "son of Isaiah", is not clearly documented anywhere. It is simply assumed to be the case, and has been portrayed as such for generations.
Samuel was born about 1712/13 - according to Harrison researchers. But no known evidence records this. It is only an assumption. He could have been born as late as 1720. Samuel later married a woman named Mary. It is known that they left VA in the 1750's and moved to Craven Co., SC. However, they still owned land in VA and did travel back and forth a few times through the 50's and 60's. It appears that Samuel was back in VA in the 1780's again, and perhaps left again a few years later. However, Craven Co., SC covered a large area. Although the Kings Mtn region of SC was Craven County in the 1750's, that county also covered the Lynches River area of SC, and there is known to have been a Samuel and Mary Harrison in that area from the 1750's on through the 1780's. I tend to believe that's where Samuel went, and not the Kings Mtn area, but I could be wrong on that.
So if the Kings Mtn Harrisons didn't come from Samuel either, from whom did they come? Let's first look at who the Kings Mtn Harrisons were.
The Kings Mountain Harrisons (aka Buncombe NC Harrisons)
The area just south of Kings Mountain is known as Clarks Fork of Bullocks Creek. It was originally Craven Co., SC. Then it was claimed by NC, first under Anson County, then Mecklenburg, then Tryon. In the 1770's, the state boundary line was surveyed west of the Catawba River finally, and it was determined this Clarks Fork land was in fact in SC, and at that time became known as York Co., SC.
Two Harrison men and two Harrison women of that area are presumed to have been siblings. Nathaniel Harrison owned 140 acres, but Thomas Harrison was listed as a Chain Bearer on several surveys in the area. I believe the evidence is clear that they were brothers. Both families later moved to Buncombe Co., NC, although Nathaniel himself had already died in 1783. These Harrison families left York Co., SC in the 1780's, moved through Rutherford Co., NC and eventually to Buncombe.
Margaret Harrison, who married Thomas Patterson, lived right next to these Harrisons on Clarks Fork. And nearby was a tract granted to Robert Cravens Jr (cousin of the Harrisons and Pattersons), and William Cravens was a Chain Bearer on a couple of surveys on Clarks Fork with the Pattersons. Cravens family history tells us that Robert Cravens never moved to SC, but rather only speculated in land. William Cravens, his brother, however did move to SC for about 7 years, from the mid 1760's to the early 1770's. William Cravens was married to Jane Harrison.
In the previous image you can see the proximity of tracts along Clarks Fork of Bullocks Creek in York Co., SC. "RP" at the bottom is Robert Patterson, father of Thomas Patterson. Above him was Robert Black, who was married to Majey (Maggie) Cravens, sister of William Cravens, and therefore a daughter of Mary Harrison (dau. of Isaiah). Above him was Thomas Patterson, who was married to Margaret Harrison. Above him was Nathaniel Harrison. Above him was Matthew Black, who was married to Margaret Ponder. I don't have the Robert Cravens (where his brother William presumably lived) plotted on the map, but his tract was bounded by Robert Patterson, as well. Thomas Harrison and William Cravens were chain bearers for surveys along with all of the afore-mentioned grantees, during these 1760's surveys.