Thanks all.

This reply from PGM:

"Yes, you can purchase the 2016 Band-in-a-Box PlusPak and 49Pak, install them over top of the 2015 Band-in-a-Box UltraPlusPak, and you will have the equivalent of a 2016 Band-in-a-Box UltraPlusPak.

Yes, you will have all available content.
Yes, you will need to install these updates over top of your 2015 Band-in-a-Box UltraPlusPak."