Well I am a bit confused now. I think I can only have one entry per category so entering both in 23 is not an option. It appears that they are using 2008 guidelines however are grouping most subcategories together; 16A-E will be one category.
After clicking around, it appears that this may not be BJCP sanctioned this year although they are using the guidelines. I will have to investigate.
basically you try to find a home for something elsewhere until 23 is the only option. One beer has nothing but spices and herbs. Both are flavoring the blonde base, not providing any sugar like a fruit. So, 21A
Treat Belgians like any other style - find a home for them elsewhere, and then if nothing fits, treat 16E as the Belgian version of 23.
Robust Porter with raspberry = 20A. Robust Porter with jalapeno = 21A. Robust Porter with both = 23.
Witbier with pineapple = 20A. Witbier with habanero = 21A. Witbier with both = 16E.
if the base beer was already a Belgian specialty, then adding fruit/spices/both to it and it is still a 16E.