As my name popped up in this message, I thought I would put in a few cents worth ...
To answer your questions, in part, and add a few more ...
The primary paper source that links John Greer (1627-1688) as a son of Sir James Greer is the following: "GREAR, James. Arrived Maryland Nov., 1674, on Batchelor, ex Bristol. Indentured. (Early Settlers Book 18, folio 152) - 2112 ... (A second listing is also shown:) GREER, James. Born probably Dumfriesshire. Son of James Greer and Mary Browne. Settled Joppa, Baltimore County, Maryland, 1675. Married Ann, daughter of Arthur Taylor and Wife Margaret, with issue: (1) John, born 1688; (2) James. (D. C., 22 Apr., 1961) - 2117." (These two entries are from A DICTIONARY OF SCOTTISH EMIGRANTS TO THE USA by Donald Whyte, 1972.) (SEE MY NOTES IN ROOTSWEB WORLDCONNECT FOR MORE INFORMATION.)
The DNA of most of the Greer descendants in America (and elsewhere) is of the R1b1a2 Haplogroup. However, there are a few who are of the I1 Haplogroup, who also show as being from Ireland and Scotland. I have long felt we have depended on our paper trails, with many inaccuracies. Dna results sometimes appear to contradict our paper trails. This is to be expected, as some of our paper trail are incorrect. Finding the truth path of our blood lines should be easier with dna use, but in some cases, we are going to have to forget what our paper trail said.
There are two dna groups that American Greers should consider: Greer, administered by Grier McFarland and McGregor of Richard McGregor. The Haplogroups are much the same in both groups, with R1b1 and I1, but the individual markers vary a great deal. I have studied these groups and markers, and I have yet to figure out if the results make American Greers more closely related or more distant, to their old world ancestors.
We have never been able to prove any connection between the Greer, South Carolina Greers and this James Greer (1627-1688). Robert Greer seems to be the first of this Greer line. This is the Greer line of an long-time, excellent genealogist, Brent Holcomb, who has done much research and publishing for the Spartanburg County, South Carolina area and South Carolina in general.
The city of Greer, South Carolina was developed as a flag station on the Atlanta Charlotte Air Line Railroad in 1873, then known as Greer's Station, named after James Manning Greer (a grandson of Robert Greer), who owned the land on which the station was built. Incorporated as a city in 1876 as Greer's, its name was officially changed to Greer in 1976.
Why do you think Mary Greer Divers was the daughter of Moses Greer, rather than Moses' brother William Greer? I would like to hear from you about this thought.
Coleman County, Texas Historian and family firstname.lastname@example.org