Using physical modeling connection ports to connect models with model block

I have two simulink models representing subsystems of a larger model. I would like to cosimulate these models using the Model block. I can use the In1 / Out1 blocks to pass signals from the lower level models to the higher level models, however when I try to add the Conn1 block for physical modeling ports, they do not appear as inputs at the higher level model, like they would if I was using a subsystem or mask. Am I trying to use the Model block in a way that is not intended or did I do something wrong when constructing this model?

Thanks.