I descend from the same Burtle line but from your Benjamin Burtle's older brother Andrew Burtle whose daughter Mary Burtle married Jonathan Goldsberry in Nelson Co, KY then moved on the Grayson Co, KY where my GGgrandmother Elizabeth Monica Goldsberry was born in 1812.
Some time back Linda Reno, a well known researcher of the Maryland records sent me evidence that William Burtle, father of your Benjamin Burtle was from the Charles Co, MD area and not St Mary's Co, MD. She sent me a copy of his will and I will send a copy of that will to your e-mail address. William died in Charles Co, MD sometime before 5/4/1789 when his will was presented for probate. It names his children and among them are Andrew and Benjamin. This William is thought to have been born in England about 1720. I have no proof of that other than the statements I find in the John Paul Burtle manuscript sent to me several years ago by a Goldsberry descendant.
It would seem more likely that your GGGGgrandmother was born in Charles Co, MD in 1789. However, I show that her father Benjamin was born about 1747, not 1773. If he were born about 1773 as you show, he would have been very young to have a child born in 1789 and besides, Mary had 4 older siblings b. as early as 1779. I show Catherine born about 1750 but no evidence of her birth. Contact me if you would like to discuss further. I do show that Mary married David Corn as well as Mary's sister, Catherine married David's brother, William Corn. Not much informaion on the Corn family. I do show that Catherine Burtle(s) and William married in Washington Co, KY on August 15, 1807 per Washington Co, KY marriage records and that Mary Burtle(s) married David Corn in Hardin Co, KY on May 31, 1810 per Hardin co, KY marriage records. Both Corn families then moved on to Pike Co, IN. I believe that Mary's sister Sarah married a Thomas Byers on the same day as Mary and also moved on to Pike Co, IN. I also show that Benjamin Burtle died in Grayson Co, KY about 1830, not Maryland. A Benjamin Burtle is listed as witness when Sarah marries and I cannot find a brother named Benjamin so figured it was her father.