The Project Manager add-on is a sync tool between a local directory on your hard disks and a remote directory reachable through FTP. All you have to do to keep the online resources and the local resources in sync is to click on a single button, and BlueGriffon will do the rest. Of course, it can deal with multiple projects.
Warning: BlueGriffon >= 1.6 required. This add-on will not work with older versions of BlueGriffon.
Warning: your ftp server must implement the MDTM feature. This add-on will not be able to synchronize a remote resource and a local resource otherwise.