Board Thread:Support Requests - Getting Technical/@comment-26151461-20150511184316/@comment-5558012-20150511205532

Star Warden wrote: You mean Append/prepend text? Yes, you can append multiple category source codes to the end of articles (ie.  ).

Edit: And to answer the second half correctly, you can use the "List comparer" tool (under "Tools" on the top bar). Add two sources you wish to use (ie. two categories) and click "Compare." If you want the pages with both categories, etc. click "Use list" and there you go.