In recent years some companies have begun to work closely with their customers and/or suppliers by sharing information to develop demand plans and execute those plans. The procedure they are following is known as:

Collaborative Planning, Forecasting and Replenishment

Explanation:

Based on the information provided within the question it can be said that the procedure they are following is known as Collaborative Planning, Forecasting and Replenishment (CPFR). This is a concept whose main focus is enhancing supply chain integration by emphasizing joint practices. Which is what is being done in this situation as companies begin to work closely together with their customers and/or suppliers.