Could you be more specific about your research? You have identified your David Hays in 1850 & 1860, but what about 1840? What are the demographics for each of the Davids in 1840 and 1830?
In 1820 there is only one David and from those demographics (four young sons, and no daughters), I guessing this is the wrong line. Looks like this David is the father of David, Amos, Elijah and probably Joel.
Who are the earlier Clinton co. marriages: William Hay 1818, Fanny Hayes 1821, George Hays 1826, Nancy Hay 1828? Do you have prospective siblings for the Rebecca you are researching? When was she born?
If the 1820 David of Clinton co., OH, is indeed the wrong one, then your David is potentially recorded somewhere else in OH or PA. If you can discover some of the demographic factors of his household from 1840 & 1830, you could match or eliminate the other Davids in the 1820 listings and perhaps even 1810.