Multi body part plastic simulation

Hi

I'm trying to run Plastic simulations on a part with 2 bodies. After right-clicking 'Shell' under 'Mesh' and choosing 'Auto', I get a message saying

SOLIDWORKS has detected multibodies in the part that you are trying to analyse... Please select the body that you want analyse.

It seems like only one body can be simulated at a time. Does anyone know how all bodies can be simulated together? Otherwise, there's no way for simulating shrinkage in the joints of the two bodies.

Thanks

SolidworksSimulation