We have 4 cats one of which joined us about a year ago.  He, Austin, the
only male, is about a year old now and is energetic and jumps on the other
cats.  One of the cats has started potty-ing in the corners of the living
room and den.  She, Lucy, the cat doing #2 in the wrong places, is about 11
or 12 years old.  The litter box has not been moved in two years, so that is
not the problem.  I read in a book that a possible reason for such a change
in behavior is Austin might be jumping on Lucy while she is trying to use
the litter box, so she avoids the box when doing a #2.  We have not noticed
her peeing outside the litter box.  The box is kept clean, very large, and
has no cover.

I'm not looking for the reason so much as I am trying to find a way to get
her to use the litter box all the time.  Any ideas?

Ty and Dusty