It's conceivable that you might be able to upgrade it to have more capability. After studying the design and determining what hardware components are needed, you'd also have to have firmware that supports the additional hardware. Beware that there may be other hardware or data modifications (e.g., inside EEPROM) needed to change the identification of which model it is.
I don't have one of these loads, so I don't know to what extent Rigol may have made it easy or difficult to upgrade the instrument yourself. But, hopefully this gives you some starting points for your exploration.