I just ran across this question. If you are still interested, I might be able to help. Lilla was my paternal grandmother. A very limited number of the books were published. I have a set, but I don't think that all of my cousins are as lucky.
I believe that my father Nelson Hitchcock has electronic versions of all of the books. Send me a note and I will put you in touch with him.
One day I'll make it to Ava. My aunt and cousins want to make a family trip in the near future.
Heidi Hitchcock Bryant