Sounds like you have good advice here. Whenever I have had covered boxes - the cats just knew what they were for but a few days of uncovered sounds good. So sorry to hear about the peeing!! That is SO aggravating! We went through it also and it is so hard to find the culprit. We were blaming the wrong cat for years until I caught the one doing it!! By that time, the entire house of carpeting was ruined - even baseboards had to be ripped out. But, you are on the right track and with two cats - should be easier. Do you suppose Marsh could have a UTI? Hope you figure it out Devon. Separating the two for awhile may be the ticket. VERY frustrating.