It's impossible. If a custom blacklist is created for a resource (IP address or user), then how to apply a customized white list for the same resource?
Only one mode option is possible:
Block all, allow selected content
Allow all, block selected content
This is so that the admins are not bored!
How to give access to one site
site.com if the site is in the blocked group "Automobile" and at the same time a customized blacklist is already included, and simultaneously both the black and white list do not work? Sadness
The interface of the content-filter needs to be properly modified! And it seems to me that you should not be embarrassed to take good ideas from other products.