CMS Filter - if keyword or other keyword

Hi everyone,

Following Scenario:

I have CMS with FAQ questions which relate to different keywords.
Once the Primary-Keyword (A,B,C…) and then the secondary-Keyword (A,B,C…)
So each FAQ can have a primary Keyword A and secondary Keyword B.

On the pages I now want to display all FAQs which have the Keyword A either set as the primary or the secondary Keyword.

How do I do that?

When I Filter for the primary keyword it only shows those questions containing it and doesnt take the secondary keyword into consideration and vice versa.

Any solutions and any help is greatly appreciated =)