I would enlist the children and explain that they are now all old enough to help with the dog. Assign each of them to walk her a set period of time a day, before school for one, after school for another, etc. Then explain to the kids and the husband that she absolutely needs to be housebroken again, and everyone is part of the team. Sit everyone down, one at a time if you have to, and explain the schedule and training. And make there be consequences - if Child A was supposed to walk her and didn't, Child A cleans up when she messes in the house, and doesn't get dessert after dinner, or something - you know what would motivate them.

She is a Shih Tzu, so she would be better with a harness than a simple collar, and that would be harder for her to escape from as well. And pick up a dog training book and make play and training the dog fun for the kids. See who is fastest able to teach her to sit, or spin, or roll over - and they can even set up a little obstacle course for her when the weather is nice outside.

But first, leash training, and housebreaking for everyone involved. And explain that if everyone does not help, there will be dire consequences.

That'd be my recommendation ....