While sometimes more income is in the best interests of the children, I would strongly argue that more time and attention from her parents is far more beneficial to her wellbeing and her outcomes in later life than having two parents too exhausted to really pay attention to her even when they are around.
 
Our support of families should be flexible enough that those parents that choose to have one remain at home as a primary caregiver have the same benefits as those that would prefer to have two parents working for the additional income. Stay at home mothers should be paid a tax free allowance that is the same as the cost to the government of sending a child to subsidized care. If your tax reform proposal is adopted, then stay at home mothers should receive exactly the same benefit.