Thank you for posting to our forums. I do regrettably inform you that the setup you would like to do would not work with just one Slingbox 350. The reason is, only one device can be connected to a Slingbox at any given time. This means trying to connect one Slingbox to multiple WD-TV's at the same time will not work. To do this setup you would need the same number of Slingboxes as WD-TV's you would like to view on.
I apologize for this inconvenience
Sling Media Moderation Team