I found a stainless steel basket/colander (I don't remember which Amazon called it) that fits inside my large crock-pot. I set it in the crock pot, pack the bones into it, and then add the water. It makes broth-making very simple, you just lift the basket of bones out.

When my mom made broth she would break the larger bones with her "meat-tenderizing hammer." I thought it was just to make them fit in the pot, but later learned that the marrow added flavor and nutrition. Or... perhaps my mom just found breaking the bones therapeutic.
:-)