Hi Kim.
There are two Descendant reports. The Descendant Chart does not contain the Marriage Status. The Descendant Book does allow for the Marriage Status. As you have found, the same Report Options screen is used for both reports, but each report has different options that are allowable.
For Unknown vs blank, you to to the Options menu, choose Customize and find the section that says "Word for Blank Records" (lower right corner of window).
Regards,
Brian