Elisabeth Gregg is also my gggg grandmother! I am descended from Mary's older brother William b 07/05/1815 in Tarbolton. He married Janet CURLE. Their son John b 20/05/1839 Tarbolton married Margaret DRINNAN. Their son John, one of twins born 09/05/1873 married Mary Jane BRIFFETT and their youngest child Margaret Drennan PETTICREW was my grandmother.
I would love to hear more from you. I can let you have more details on my line if you are interested.