When the creators of Curious George, Hans Augusto Rey and Margret Rey, were living in Paris, France, in the mid-'30s, they created a series of cutout figures for the publisher Hachette which included a set based on Mickey Mouse and one on Snow White and the Seven Dwarfs, both released in 1938.
I believe we could probably learn how they got involved in this project by checking H.A. Rey's journals from those years, which are preserved in Hattiesburg, Mississippi, in the Grummond Children's Literature Collection at The University of Southern Mississippi. [H.A. & MARGRET REY PAPERS (DG0812) (V. Personal / C. Journal and Diaries / 1. Personal Journals & Diaries / 166/1-20 H.A. Rey's annual journals, 1936-1955)]
Any volunteer to go there and check?