Why, in Civicase, is 'other relationships' purely additive & why do they show up on every subsequent case?
I found the answer here in an old forum posting  Civicase creates a group called 'Case Resources' into which it drops any contact you add (as described above).  So to remove these from all cases you just edit this group.  Phew!  Wasted an hour or so, but now a little wiser!