1. No, you can't get HDMI through a coax cable.
2. I'm not clear on what you're trying to accomplish. Most TVs do not have video outputs of any kind, since they are simply display devices, not signal sources. You don't say where the HDMI that goes to your 65 in. TV is coming from. DVD player? Blu ray? Cable or satellite box? Do you want the same film or program to show on all three TVs at the same time?
Please list all equipment, including make and model of the TVs and source components plus AV receiver or other sound device so we can comment on this intelligently. There's really nothing anyone can tell you based on what you've posted so far.
Regards,
Joe
