Cats who urinate in bad places can make themselves unfun to live with.
It’s a problem you want to correct early not only because bad habits become established quickly but for cats, the scent of old urine is a means of intercat communication.
If you have a few cats a political debate can degenerate into some rather strong feelings getting expressed all around the house. It isn’t pretty.
The politics of indoor feline life usually has only one responsible cat, but there may be more.
I suggest a methodical system of isolating your cats to different rooms to learn who does and does not need behavior management.
One technique is the use of a fluorescent dye that your veterinarian can inject beneath the skin of the most likely culprit. An ultraviolet light shined on the urine of this cat will show a bright green color in a dark room.
It sounds like pretty slick crime detection but it’s less than fully reliable. Some cats produce more dilute urine making the evidence a bit weak in some cases.
You are more likely to score a conviction with careful observation and circumstantial evidence.
Take your time and watch like a hawk.