#1 There are a lot of products out there, but in my experience the smells never goes completely away. We have even gone as far as pulling the carpet up, removing the pad, sealing the floor, have the carpets cleaned from the front and the back, and then getting new pad....it still smells on hot humid days.
2. A 9 year old cat could be going through several things. Usually if it is a medically issue, she will be diabetic, have kidney disease or a UTI. If it isn't medical, then it is probably due to the move. YOu should definitely put a litter box in the basement, but also look at where the other one is. If it is too near their food, they will often not want to use it. Also, if it is close to the washer, or any other appliance that makes a lot of noise,they can quit using it as well.
3. She may be very upset about the baby too. He's what, about 8 mos? That means he's active, which is a big change for a kitty that hasn't had kids before.
4. Is she your only cat? You should have one litter box for each cat, plus one more.
5. If the carpet is light in color, you should be able to tell what color the uring is. Is it bloody? Dilute or very concentrated? Bloody would lead me to think UTI...Dilute would lean towards both diabetes or kidney disease. Does she drink a lot of water?
5. IF she is really picky about a clean box, then I would suggest that you also try the litter miad. It cleans itself after every potty break, and it traps the smell inside a canister as well. We had a cat that was picky, and only wanted her litter box in the basement, where we never spent any time, so it was often forgotten, but she was also a very shy/nervous cat, and I was afraid that a robot tiolet might scare the heck out of her, but I finally broke down and bought one, and she LOVED it!! Fot the first week, she would go to the bathroom, watch it get cleaned, and then hop right back in a go again. IT was so nice!! Adn then you just have to toss and replace the canister about once a week..