We certainly promote all four our HD Channels! However, we don't promote them as if they were separate stations. We treat it kind of like a website where the HD1 / FM channel is our home page and the HD2, 3 and 4 are additional choices in our "menu."
Here is how we promote it on our site:
Our full schedule
https://www.kvcb-online.com/broadcast-schedule
Our HD info page:
https://www.kvcb-online.com/hd-radio-information
We're a school radio station so our goals may be different than other stations that may not be as hyper-local. The students have 96 hours a day to program. You gotta love radio!!