I had another thought: the 10 years married might be her TOTAL years -- with Mr. Vinson and with Levi Knight?

I can't tell if the number of years for Levi = 2 (crossed out) and then 7 OR 27 years married...? Maybe he started to give his total as twenty-something (was widowed) and then changed it to 7 with Martha.

If you can narrow down the marriage date, you'll have a better time of finding the marriage record.