You point out or rather get them to see how it works or doesn't work for them and then how much does it bother them? Bringing up ex like: I have tried to work out a budget, I find it tough and wonder how you have it figured? Our plans from the beginning put the kids' first, kids take a lot of money to keep up, will we be shortchanging them too much? We are both used to having back up with the kids and work - have you though about to manage kids and working fulltime? at the end of the day/night? Probing questions, just don't start a question with "why", use how, when, who, what. Think in terms of using words that get her to think before answering. You don't want pat answers - she needs to think in order to see what choices she is making and how it will affect everyone's lives forever. Ask her how she sees things working out separately in one year, five years, ten years down the road.
