Understanding that is the understanding of the "demand" of themselves is the knowledge that they need so they can respond appropriately. Once those needs have received a response, we would be happy.
Understanding that is understandable "Demand" their is to know what they want in order to respond appropriately. Once those needs have been met, we will be happy.
Understanding, that is to understand the "needs" of their own, know what you want in order to respond appropriately. When those needs get response, we will be happy.