Training, training, training. If they’re marking, keep them on a leash so they can’t get far – they haven’t earned the right to have full roaming privs in the house. The second they start sniffing like they’re going to cock a leg, correct them. Rinse, repeat. Belly bands can help, but I wouldn’t rely on them to be your only training tool.
Also: CRATE when you cannot supervise, and clean the heck out of the furniture with an enzyme cleaner.
I usually cage rest dogs like this for at least 6-8 weeks and recheck them at least once or twice during the this time.