As you know Debbie, my Nugget was pooping outside the box after his little baby PeaPod left. Fortunately he only pooped just in front of the box and no where else. It took me almost 3 months to get it under control.

In regards to Carol's Oskar, has there been any kind of change in the house?
Renovations, moving furniture, moving the litter boxes, different litter or anything new that was added? Has she thought of adding an extra box? Did she bring Oskar to the vet to confirm it isn't anything medical?

These are just some things that I can think of off hand.

Here is a little info that I got off a site that might help:

Litterpan problems are very common in cats. It helps to think about this problem from the cat's point of view sometimes when trying to deal with it. Cats like to have a clean, inviting place to defecate and urinate. Remember some of the dirty bathrooms you have had to decide whether to use or not, and you can relate to this feeling. So it is very important to make the litterpan as attractive as possible for use.

Keep it very clean. Use a litter that the cat likes. The clumping type litters are the most commonly preferred litters in surveys of cat preference. If you are not using this type and your cat has a problem, it can help to switch.

The litterpan should be in a convenient, but private or at least semi-private site.

It helps very much to have one more litterpan than you have cats. In multicat households where this is impractical, it can help to give the problem cat access to the litterpan, alone, for several minutes twice a day.

When a cat is using a place in the house other than the litterpan to urinate or defecate, the opposite is also true. You want to make these spots unattractive. Cleaning the area with an enzymatic cleaner so the cat is not drawn back to the same site helps. Putting plastic or aluminum foil over the area, if possible, can be very helpful. Putting the litterpan at the site the cat prefers, then very gradually moving it to a site you like can be helpful.