The 612 was originally shipped with UHF/VHF capability activated. The UHF being activated doesn't prevent it from using an IR remote.Per Zach's comment, and no disrespect meant, but as has been said, the users here are hardly the average user. With that said, when a customer has a very unconventional and non-standard layout, you're not going to find a lot of call center folks who can help. Having 7 TVs (wow) hooked up to a single 612 isn't normal, and while the CSRs will do what they can to help, please realize if you set up a very unusual setup like that, you're mostly on your own (or should ask here, it's far more likely someone here can help with an install like that).
Your last comment sort of hits that point. "Why can't the 612...", and you ask for a configuration that Dish doesn't really support. There's just not a logical reason to set something up like that, for something that 99%+ of the user base isn't going to use or need.
For example, if you were to take your wireless router from a telco, have it hooked to boosters, some kind of antenna to enhance signal on a large property, or something like that, you're not going to get much luck if you call the telco for help on that.
In the earlier days of "C-band"/ small dish it wasn't unusual to combine an OTA antenna and a CH.3/4 satellite signal and distribute it through out the house. Today with digital satellite very little TV broadcasting is below Ch.7 so CH.3/4 has no interference.