Great ideas about pepper and the box! To be honest, I'm not sure what
they're doing in particular, just that when my hubby said, "I hope the cats
aren't bothering you," and I said, "They're not messing up your garden or
anything, are they?" she just looked sheepish and nodded. So I don't know
if they're chewing, digging, pooping, or what, but the box sure couldn't
hurt, as I know they use their box a *lot* less when they're going outside a
lot (virtually never, unless I don't let them out for a day), so they must
be going somewhere, and her garden is as likely a place as any. I have seen
one of them use our yard, which is a bit of a wasteland at the moment, so it
stands to reason they very well might be using the nice soft soil in hers as
well. And the pepper thing is great, too (similar to the mothballs, except
no question as to toxicity), I'll definitely have to try that! I was also
thinking some kind of extention for our garden wall; before we bought the
place, the landlord replaced the crumbled half of the wall with a fence
(after years of hassle from the previous neighbors, since before we moved
in!), and that's too thin for them to jump on (I *think*), but part of the
remaining wall is low enough for them to jump on and over, and they do, so I
was also thinking maybe something to extend that a bit higher, but not sure
what....but anyway, those other ideas sound really helpful, and will
definitely try them!

Thanks to everyone who responded, what a great bunch....

Ann