How to add a Not condition in 6wtags?

Hello, All the search results using 6wtags are based on AND condition, which is not solving all the search criteria of the business use cases.For Ex: As a User, I want all the citizens who has citizenship of only US but not Canada. There are many citizens who has dual citizenship of both US and Canada, should be filtered out of the search result.

How this can be configured? Please suggest . Thanks in anticipation