Together with the VEGAS Pro 16 installation you receive 1 or 2 BCC11 units for free.
If you already own a BCC10 license, the installation of these units remove all BCC10 effects and leaves you withthe installed BCC11 effects.
I found following trick to get the BCC10 effects that are not included in the BBCC11 units I installed back:
At the end of the BCC 11 unit installation you are asked if all unlicensed effects should be removed. Answer "YES" to this question. The result is that only the licensed BCC 11 effects are shown in Vegas Pro.
Install all new BCC 11 units you have. (Key and Blend Unit, Lights Unit, .. ).
Make sure that you have activated all BCC 11 units you have and that you said "YES" to the question "Delete all unlicensed effects" at the end.
Now reinstall BCC10.
After this process I had all new effects from BCC11 and all old effects from BCC10 in my VEGAS 16 effects list.
I hope this helps.
Harold