@jenebene I know it worked on my mom's cat, but it also left a lighter marking on a light beige couch...
There are certain spices cats hate, maybe try that, too (not necessarily on the chairs... If the floor around the area is unappealing, they won't get too close)
Thanks for the tip @NapsAndSarcasm
Wonder if that would be less effective if you diluted the lemon juice in a little water…