A downhole tool comprising a housing a passage disposed within the housing a seat configured for deployment to a plug-receiving position for receiving a plug being deployed through the passage a key profile for effecting actuation of the seat to the plug-receiving position in response to registration of the key profile with a matching key of the plug being deployed through the passage a port extending through the housing and a flow control member configured for displacement, relative to the port, in response to application of a sufficient net force effected by a fluid pressure differential that is created by supplying pressurized fluid to the passage while the plug is seated on the seat, wherein the displacement of the flow control member is from a closed position to an open position.