How do I rsync /source/new-folders recursively, while skipping recursion on folders that already exist (at root-level) in both /source and /dest? Make sense? Example inside.

Let's say these are in sync:

/source/folderA/files /dest/folderA/files 

And I fiddle with some files in /dest like this:

/source/folderA/files /dest/folderA/files.tar 

Then add folderB to /source like this:

/source/folderA/files /source/folderB/files /dest/folderA/files.tar 

I want rsync to do this:

/source/folderA/files /source/folderB/files /dest/folderA/files.tar /dest/folderB/files 

Is this possible?

Thanks!