Instead of Merry's Documents\xyz\*.* use *\Merry's Documents\xyz\*.
If that still doesn't work, try changing Merry's Documents to just Documents in case it's the real path and the longer name is just a display name. (Don't think that should matter, but it's possible, if those are the Windows-provided documents folders or copies of them.)
It works for a few folders but the process is unwieldy with, say, ten or more folders.
For this reason, I would request a feature where simply selecting the folders, opening the Synchronize pane and hitting Compare synchronized those selected folders.