Abstract: A reusable insert designed for off-the-shelf covered containers, such as infant feeding bottle having a storage compartment for powdered formula, a top opening (32) to the compartment, a bottom opening (36) to the compartment, closure (40) for closing the bottom opening (35), and an actuator (20) that is guided for vertical movement within the housing for operative engagement with the closure. The upper end of the actuator extends below the nipple which is attached to the infant feeding bottle so that the user can apply downward pressure on the actuator through the nipple. Downward movement of the actuator causes the closure to move from its upper closed position at the bottom opening to a lower open position spaced from the bottom opening of the housing to enable powdered formula to be released into the chamber of the infant feeding bottle.