The method and structure to expand, upgrade or repair of a multichip package

system with a multi-chip package (MCP) (102) having a plurality of chips (104), a lower package substrate (108) for interfacing with a printed circuit board (PCB) (306) and an upper package substrate (106) as a interface between the MCP (102) and a retrofit housing (108) is used; and a retrofit housing (108) which is attached to the upper package substrate (106) of the multi-chip package (102) to change a functionality of the multi-chip package (102), and is attached to a detection circuit (110) for detecting the presence of a retrofit housing (108) to the upper package substrate (106) of the multi-chip package (102) to change a functionality of the multi-chip package (102).