To specify a SharePoint sublibrary without migrating the parent library, simply enter the path of the sublibrary when you set up the items in your project.
For example, you have a library named "Documents" and a sublibrary within that, named "MigrationWiz". To migrate only the "MigrationWiz" sublibrary, enter "Documents/MigrationWiz". This way, only contents of "MigrationWiz" will be migrated.
Note: The parent library "Documents" will be migrated for the sole purpose of storing the "MigrationWiz" library. However, no other files or folders stored in "Documents" will be migrated.
You will need to add a new line item in your project for every sublibrary to be migrated.
For example, "Documents/MigrationWiz" and "Documents/Special" are two separate libraries that will need to be migrated separately. Be aware that this will require two separate licenses.
Also note that when specifying the parent library, all sublibraries within it will be migrated automatically.