An apparatus includes a daughter die (DD) logic, and an arbitrator connected to the DD logic, and connected to an external testing device and a main die (MD) included in a multi-chip package (MCP). The apparatus further includes an enable logic configured to receive a message from the MD, based on the received message, determine whether the MD or the external testing device is enabled to access the DD logic, and based on the external testing device being determined to be enabled to access the DD logic, control the arbitrator to enable the external testing device to access the DD logic.