I would be happy to look over the Chicken Lady painting signed Mack for you. I used to work at Illustration House in Manhattan with ***** ***** who passed last year in his late 90's. We handled, authenticated and sold a large number of NC Wyeth original illustrations there.
You can send over images at your convenience.
This is a conversation thread, so we can parlez back and forth. I would not have been able to expound much at the beginning without images, as those are rather crucial. To start, what information is it that you are seeking and we can go from there.