Am not involved with this project, but looking at it I assume these records are taken from the WPA listing of marriage records compiled in the late 1930's. The WPA ran out of money and disbanded before they completed the project and so only 86 of the 92 counties were included. Those for
Sullivan county included in the Family History Library which is the basis for this listing included those from 1830 to 1850 only. May be wrong but don't think so. Good luck. Don