North American Fruit Explorers mailing list at ibiblio

[Alan Haigh <alandhaigh@gmail.com>]

If you want to know about the possibility of graft incompatibility ask a
nursery owner that grafts a wide range of paw-paw varieties, it would
probably be more useful than searching the literature.

Nick England or Mike McKonkey come to mind.

I find this theory doubtful only because I haven't heard of it being a
problem when reading comments over the years of scores of hobbyists that
regularly graft them.  Sometimes the people that do have information that
people that read about doing don't.