Cloth simulation

I need to simulate a plastic bag that contains dogs in it. I´m attaching an image of the bag. It has to give the idea that it has something heavy inside and it moves a little, like a dog would. I only need a working system that I can use, no render, no textures, nothing, just the file and the simulation ready to go.
This must be done in 3Ds Max, ideally with tyflow.