How would I implement row level security using multiple columns to create roles.  For instance, I want one user to have access to three attributes in one column and two attributes in another column.  Can I add the column to an existing security table that only has one other column to filter on?  Or would I need to join another security table? 

If I add another column to an existing security table this may cause issues with users that need full access to the new column while others are being restricted.  Any help is much appreciated.