In our Vegas 24.1, the outside line would come in to the amplifier (switcher) that would hook in with the roof-mounted tv antenna. I just ran that wire directly to the dish box.
I have since gone with a roof-mounted dish so I manually swap wires if I ever need to use a portable antenna run in from the outside connection (if the roof one is blocked by trees).
We never use the air antenna.
I still use the remaining coax wires that go to all the tvs through the factory splitter to send the hdmi signal from the dish box .. works really well with this:
https://www.amazon.com/gp/product/B01F6XGTO6
(need a transmitter and 3 receiver .. the receivers are powered by a USB port on each tv so it all works really well)