So, I just checked and I assume your target David Darst is "David Martin Darst, CFA, is an American financier, educator, and author." (Wikapedia). I did a quick check on Ancestry.com and there's various trees and sources for John Mathias Darst including a death certificate showing his father John Edward Darst. If you have Ancestry, you may play around there and see if you can work your way back. trying to find a common ancestor. However you will find things easier if you ask to become a member of WikiTree so you can make the best use of the material here. I'm not sure if you can do some things as a visitor, but if you click the "find" at the top of the page, there is an option for "Surnames" and if you navigate that you'll get to the Darsts who have been entered into WikiTree so far. There are 117 of them with several Davids among them, including one with no dates who could in theory be the one you're looking for. To become a member you need to become a "volunteer" so that could be your next step. Or if you ask nicely <g> I'm willing to put in some more time to try the find the link. (assuming there is one.)