It seems we are at an impasse.
I wish I'd gotten this on video. Millie backed up the ramp all the way to the porch. But she was not happy and grumbled the whole way. Step-step. Grrr . . . roof! Step-step. Grrr . . . roof! And then a final bark as Maggie got up onto the porch. Woof-woof-woof!
P.S. I was having problems uploading pix. This is the only one I could get, but it's the best story!