And why did alans_vzw write to CMV-KV on 12/07/2018 at 9:09 AM
"You are correct, you can always do a voluntary buyout for the one you're paying for and your monthly credits will indeed remain intact for the free one you added with a new line. To be 100% sure of this, I researched the BOGO promotion we ran for your Galaxy Note 9 so you're safe to pay off your upgraded line. As long as you don't transfer your service to another account or disconnect either line, the 24-month promotional credit for the free phone still applies."
This was in reference to a BOGO promotion of the Galaxy Note 9 that was being ran in August of 2018. The same BOGO promotion of the Galaxy Note 9 that I bought my phones under.