Hi Mia_,
I just watched your first video (actually I watched it 3 times..). You have some useful tips there (giving each rig a name and different colors for the dopesheets. But I'm lost in how to do it. The thing is that I cannot clearly see what you are doing and were in the screen I should be. Perhaps you could add some colored arrows or something like that to pinpoint were to look? Just a thought. In the meantime I will give it a try. Trial and error seems to be my way of learning.