Monte Carlo simulations with a multi-process circuit

We are designing a module that will be made from two die bonded together to form a single device.  Each die uses the same process, but come from different wafers.  Some circuits will be split between the top and bottom die.  I have used MTS options to cover corner cases between the two die, ie simulate the bottom circuits using an ss corner while the top circuit uses an ff corner.  But I would like to simulate some circuits using Monte Carlo.  It is not clear to me if the top die models and bottom die models will be treated independently, or if it will simulate both halves as if they are both on the same wafer.  I want to see results where the process variation is completely independent between top and bottom, but the matching is still good between devices on the same half.

Can you tell me how to get Monte Carlo results that show me results when the process varies independently for two sections of the circuit hierarchy, and mismatch occurs between devices on the same half?

Thanks,