How to generate Simscape composite model from Simulink?

Essentially, I am trying to define a simscape model, then use the simulink graphical interface to generate composition of it, and then generate the composite simscape model.

I also want to dynamically generate composite models from matlab. Any help would be appreciated.

[Yu Jiang]

By "dynamically generate", are you referring to adding components to a Simulink model via MATLAB command line?