Can multiple WDC MyCloud Devices Sync to each other

I plan to setup the WDC MyCloud to sync a Windows File Server inside the network. Is it possible to sync multiple MyCloud devices across the internet?

Use SyncThing for sync via internet.
If available “real” (“White”) IP address - you can se rSync + Cron.
For LAN - Samba can sync files between all network shares. Google for it.