I removed the cushions and lined the corners and all along the back of
my couch with cardboard, then duct-taped it together and to the seat.  I
didn't tape it to the back of the couch, because the tape will pull away
when humans sit on the couch.  For the corners, I used actual corners of
cardboard boxes, cut down to size so the cardboard doesn't show above the
cushions.  The cushions hold the un-taped upper edges in place.  So far,
so good!
 
Nancy and critters
[Posted in FML issue 3531]