Welcome to YorkieTalk Alex.
My older boy was the same as Nancy's Joey with piddle pads. He wanted them changed after each use, but he eventually grew out of it. Sometimes he would play with the piddle pad when I left him in the house alone. You could try putting a second one down for awhile, so that she has two to choose from.
I agree about the cost of raising two dogs. The most important thing to remember is that you have to plan for the possibility of a costly medical emergency. With 2, the risk increases. I was worried that my first boy was lonely, and he does enjoy his brother, but I think both of my boys would be fine as only children. As long as Duchess has loads of attention from you when you are home, she will be fine.