Susan, I believe the way Charlotte approached multiple languages was layering them in, beginning with oral. So it might look something like this
Grades 1-3: oral French
Grades 4-6: oral and written French; oral German
Grades 7-9: oral and written French; oral and written German; oral Italian
Grades 10-12: oral and written French, German, and Italian
I don’t know that there is a preferred order in which to approach the languages. It seems like the same layering idea could apply to any three languages.
Hope this helps!