My maternal grandmother, Irma Nell Burkhalter Blevins, went back as far as John Burkhalter, Sr.(1723~1784). I'm descended from Martha's older brother Isaac (1772~1847). I just recently stumbled on this massive thread and am filling in my gaps, but I would gladly offer any help that I can from her and my research. Feel free to email me, just put "Burkhalter Family" or something similar in the Subject line so I don't think it's spam and delete/block it!
In the meantime, I'm trying to figure out how to input what I've got in a semi-organized and rational manner.