First of all ' shame-on-you' for changing date from 1773 to 1784 and wasting a half-day of my research.Also you know that much on the internet is just made-up data like yours.Even the LDS records are very IF'y, unless dealing with the IGI which are copies of primary documents.
Graciously, LOOKING again in my records for Elizabeth born in 1773.
Possibility # 1. The Robert Jr. Killed by indians I told you about, she could still be his child. [YOU WILL HAVE TO DO RESEARCH TO FIND MORE DATA ]
# 2.NOT the Eliz d/o Samuel because her husbands were Mr. Ellis and Mr. White.
# 3. Your Eliz 1773, could be child of Thomas Gragg (1715-Northern Ireland; a son of John Gregg 1690.This Thomas left will dated 1773, naming wife Elizabeth, 3 daughters; Ann, Mary and Elizabeth and sons Henry and William.Thomas's wife's full name was Elizabeth SAMPLE d/o Samuel Sample. The appraisers were appointed 17 Aug 1773.Little Elizabeth would have been bornabout 3 miles North and West of Harrisonburg, VA. The Court records show that little Eliz was bound out to her brother William in 1780.Her sister Mary seems to have married JAMES REECE.Augusta Co. Court records payments from the estate to Elizabeth until 1795.
[CHECK FAMILYS OF REECE AND SAMPLE ] They may provide more information.
#4. Another Son of John Gregg 1690 was William Gragg born about 1735-N. Ireland. He married Elizabeth Martin.Their eldest son William Jr. was born 15 Apr 1758. They had a daughter Elizabeth (dates unknown ) and during the years of 1769-1777 they lived in Albemarle County VA and this data found in the Augusta Co. Fee books. His will proved in Albemarle Co. October 1789.
I have no further information.
You will have to stop relying on others research and dig into this yourself by looking at surviving records in Albemarle and Augusta Co's VA.
I see no other possibilities to fit your Elizabeth into our family.Again Best Wishes.. Let me know when you solve this very interesting mystery.ByeMaurice