A family of Microsoft word processing software products for creating web, email, and print documents.
The simplest would be to disable the auto spell check. The other option is to switch the proofing language as and when you switch the language you are typing in.
You could also look to type relevant section in their respective languages and then copy paste them to a main document.
This would provide more information on spell check in a different language.
http://mac2.microsoft.com/help/office/14/da-dk/word/item/987fc20a-b6bd-49db-8ba1-6a263a924b41