OK...I did it by the book
I called the 1-800 # on the back of the BB. The res agent quoted me the same rate I saw online, but when I asked about the Summer Sleepover promotion (same as the best available rate), she said I couldn't use the BB with that rate
So...I decided to just book the BA rate to make sure I can use the BB. Oh well... It would have been nice to get another BB, UA cert, and breakfast for the same rate! UGH...