A CEC propagation control function, operated by a manipulating switch coupled to a first, second, and third HDMI-CEC devices, enables the manipulating switch to receive a CEC block from the first HDMI-CEC device, pass the received CEC block to the second HDMI-CEC device, and prevent the third HDMI-CEC device from receiving the CEC block, although the manipulating switch is coupled to the third HDMI-CEC device. The manipulating switch may also be implemented as a network.