How to handle this translation process?

I have a scenario regarding translations and I'm not sure what the best practices for handling it is. Here is the scenario:

1. We have a page in English

2. We create a translated Language Copy of the English page in French

3. The translated French page is later edited to add France-specific content to an existing Text Component after the page was translated

4. We decide to change some content on the English page in that same Text Component

5. The page gets re-translated into French to include the new English content

6. The French specific content that was added in Step 3 is lost.

How can we maintain content that gets added to a translated page after the page goes through another translation?