Steve -- the latest info seems to be leaning to Enoch Doster as the father of Mary.Ruth Davidson provided the following info to me:
"Here's a little more information on this family.Mary Davison married Enoch Doster and had ten children according to the 1820 and 1830 Census Record of York Co. ALThey named their first daughter Margaret Amanda Doster and she married Clark Robinson.Elizabeth was born about 1810. Martha was born aout 1812.A daughter that I don't know name was born about 1814.John Doster born 1818 died 1891 in Montgomery Co. Mississippi was married to Louisa Eliza Boyd. James Doster married Rhoda P. Clark. both died in Jackson Co. GA.George Smith Doster born abou 1821.Jane Doster born about 1824 married James Black Evidently James Black buried in Lamar Co. AL. A daughter that I did not have a name born about 1827/28 and William David Doster born about 1829.
The "latter" daughter that I did not have a name for is probably your Mary E Doster born 24 Dec 1828 and married to Joseph Black.I would think that your John C. and Elizabeth Black are the parents of your Joseph, James who married Jane Doster and also the younger John Black all buried in Lamar Co.Sizemore Cemeter."
Of course we know that John C. is the father of Joseph, my gtgtgrandfather.The interesting part of this is that there is a female Doster born at about the time that we have a birhdate for Mary E.However, that is still no proof.So we keep looking.Since these families did not get to Alabama until shortly before 1850, there may be some additional records in SC that we need to look for.