Just a thought - have you tried removing the living room litter box
and seeing what she does?

  That aside, 3 litter boxes for two cats seems like overkill...

ttyl,
Amur_

Ok, does she stand inside the box while weeing outside, or is she standing
NEXT to the box? If  she is standing inside the box with bum out, perhaps
buy a taller box,or enclosed one and see if that works.

Is she always weeing at  the same spot? Did you try moving the box to the
spot she prefers?

If its been 2 years, it has become a habit now,and the area around the box
could be smelling like a bathroom still to her, even tho you may think its
clean.Remember the cats noses are much better then hours, and they use smell
as a primary sense, not sight. So you need to work on two things, breaking
da smell and the habit. I don't know the product you mentioned, but you
could try method I find works well:

Wash that carpet (box,don't forget outside the box, and wall) thoroughly
with a biological washing powder, or some specialised shampoo that contains
enzymes which would munch up the
parts of urine. We are talking serious scrubbing here, because even though
we can;t smell it, cats, believe, can. After this has been done, take
vinegar (in colour matching your carpet :)- probably clear malt one would be
the best and strongest. Yes that stinks, but it works wonders as cats hate
that smell. I am not
certain if it neutralises the urine in some way as well or not, but you must
definitely put the vinegar on the spot. Let the carpet dry. Perhaps speed up
drying with some hairdryer treatment. Lastly, when dry, you
could use some Downy fabric conditioner to kill any residual smell left.This
one is for you really.

Now, buy/borrow another (enclosed) litter trey and place it in that spot.

OR, get a dish with dry food and place it on that spot. Cats are clean
animals and will not urinate near their food. Even wipe the carpet with some
dry food to gain the smell of food. I know this works as my friends done it
on their cat/carpet.

Finally, you may need to consider replacing the carpets,but the flooring
underneath could be soaked sothey will need treatment as well,before the new
carpet.

Lastly the other poster has asked a fair question,do you really need a 3rd
tray there as well? Perhaps move it all together in another location,and
start putting the dry food down in this room.

Good luck,

Gee

What happens if you remove the living room box altogether?
Can you place something underneath the boxes which is easier to clean like a
rubber mat?

Carola

Try using a carpet extractor with 1/2 cup of BORAX, adn 1/2 cup of Washing  
Soda (both available in the laundry detergent aisle at the grocery store).  
Don
't use any more soaps on the carpet, just the borax and washing soda  
solution with hot water in the clean water tank on the extractor, go over  
the carpet in the affected areas several times, this will remove old soap,  
and leave a coating of borax behind wich will inhibit mold growth, and  
also kill fleas, and other insects that travel in the carpet without the  
use of strong poisons. The borax and Sodium carbonate (washing soda) will  
kill and remove most odor causing agents without leaving any perfumes  
behind, and is non toxic to you and your cats, it's probably the best  
solution to clean carpets with, because it doesn't leave soap residue  
behind, wich will pick up more dirt anyway. If you have a particularly bad  
spot of carpet soiling, spot treat that area with a spray on carpet  
cleaner and a scrub brush, then go over it with the borax/washing soda  
mix. The alkalinity of the mixture makes the soaps more soluable, and they  
will work better.