We had three plus a dog we would put on a leash when we traveled. The dog did fine, one of the cats did as well as the dog, (he would do anything to please us), one would fight it constantly, (he always rebelled against everything unless something was after him) and the other we just drug him behind the rest of the crowd.
My husband tells her: you carry your end, and I'll carry mine, and she grabs the leash about a foot from where it's fastened to her harness. It's so darned cute!