I am a descendant of Philip and Mary Grove of Washington Co., MD -- who settled in Greene Co., PA by 1810 or so. Mary is still alive in 1850, her age given in the census as 93 and her birthplace as MD. (She was living with her son John, who would later moved on to MO.) I had estimate the marriage of Philip and Mary as 1780, and she surely must be the Mary Ekell who married Philip Grove on 22 Nov 1780. Philip Grove was born in MD about 1756 and is on the census in Greene Co. in 1820. He does not appear in 1830 and presumably was deceased.
There are several of Philip and Mary's descendants working on this line, though we haven't been able to get back beyond Philip so far. He would seem to belong to the family of Hans Graff, though they do not have him in their records.
It was good to find your site, thanks to a cousin who recently located the marriage record. I have a letter written in 1818 by Philip and Mary Grove to my gggg grandfather, Balzer Bentzel, who married their daughter Lena (Magdalena?) Grove in Washington Co. around 1806. I also have a list of their children that was written down by Balzer and Lena's grandson, my gg grandfather, around the 1880s. Be happy to share with you.
p.s. You can probably find the letter on line. Type in Balzer Bentzel or Philip & Mary Grove on Google. I've posted it several places.