Pricing, multiple vehicles, and discounts

I have searched for the answers, but everything I’ve has been very vague. I have been a loyal GM customer for over 34 years. I have owned GM vehicles primarily, with very few exceptions. I currently own multiple GM vehicles. Of the six vehicles I own, two are equipped with OnStar (the GTO didn’t come with it and would likely have a sunset version if it did, two are HD motorcycles, and one is a Jeep - inherited). The two OnStar equipped vehicles are a 2015 High Country 3500 Silverado and a 2019 Z06 Corvette. I am considering getting an OnStar account for these vehicles to utilize all the features I paid for when I bought them, but I do not want, what is equivalent to, a full on household bill for a service I would barely use. I can only drive one vehicle at a time (I am single and my kids are grown and moved out – I’m the only driver of these vehicles) and I work for home, meaning I rarely drive to begin with. Therefore, I was inquiring to see if it was possible to get a multi-vehicle discount and/or a military veteran discount (I am a 30% - likely to increase soon – disabled veteran) for OnStar services for these two vehicles. I am also an AT&T subscriber if that helps (I know the LTE service OnStar uses is AT&T).  If not, I’ll just keep using my phone as I have been for years, since I literally get all the same capabilities, just not “built-in”.