Setting up a connection across 3 screens in 3 office locations

IF the tvs are smart tvs and have web browsers, then having a timed slideshow in a website would work, if not, the TVs should be connected to a computer and use some sort of meeting software, ie GoToMeeting, Team Viewer or other software from the central location to show it.  It does require that someone at the remote sites log into the master or vice versa.