This is standard. Since you are living as a family unit and she is working, her income is taken into consideration. And yes, it is quite legal. It is a requirement of a rehab if you are looking into the reasonable and affordable option. Without her income, they wont take into consideration the car payment or insurance since it is not in your name...only your bills which would be half of the rent, half ultilities, half child expenses and half food. You can't have it both ways.