If I’m using makehuman to create base humans & importing them into blender with rigify or mhx2 exported rigs, how can I add to the rig? the only bones I find are custom shapes & deformer’s. I want to give my models dynamic breasts but can find the bones used in the tutorials. Can someone point me in th right direction?

When you import mhx2 you need to tell the import script to add the rig.
There is a checkbox to override exported data. Scroll to the bottom and you can then add the rig you want from the drop down menu.

made all the difference. Thx so much.