I just have them in the same folder Applications/Band-in-a-Box/
Band in a Box.app
Band in a Box 2017.app
Band in a Box 2016.app
Band in a Box 2015.app

you can extract just the Band in a Box.app out of an update package using something like Pacifist and rename it Band in a Box 2016.app

That way you should get the newer RealTrack & Drums in the 2016 picker.