I have a sneaking suspicion this person doesn't actually exist...
A new name has been added to the credits of the 1928 film Steamboat Willie, supposedly providing the voice of Minnie Mouse. Her name, we are led to believe, is/was Charlotte Jamquie. The problem with this (besides the fact that Walt Disney was already credited as the voice of Minnie Mouse and every other character in the film) is that I can't locate any biographical information online about this Charlotte Jamquie on any site except ones that appear to be copying from IMDb. Of course, there's always a slight chance that some information about the mysterious Charlotte Jamquie exists in print media which has never been uploaded on the internet, but, I have doubts.