Is there any other place that might hold information for Alexander Co?..

1.I have a couple married ca 1850-1851 No record found, although the brides sisters' marriage was found. If they went accross the boarder to marry where would they have gone to. They lived in the Ciaro, Thebes area.

2. This couple were both death by May 1863. agin no record found. And a quick scan of the books published with cemetery indexes did not find them.

I am at total loss on how to continue with this search.
any suggestions?