A little over a year ago I moved with my two 7-year-old brother-and-sister
cats into an apartment that already had two cats.

My female cat is "guarding" one of the cats that was already here, and is
not allowing that cat any access to food or the litterbox.  She only gets
food when I can retrieve her from her hiding spot and intervene to take her
to food.

Is there any way to get my cat to stop doing this to the other cat?  It's
not much of a life for the other cat, almost permanently holed up inside
the box spring....

THanks in advance for all replies...