The name Christmas (or sometimes Cris) Mitchell appears in the following Latent Image catalogues:
1973-Fall, 1974-Spring, 1974-Fall, 1975-Spring
but as far as I'm aware all have lacked any pictures of her.
There is a 1969 Edmund Leja model called Christmas Mitchell shown
here,
here, thanks to Joszka.
It's not the most common of names.