Overwrite a language string in a parent theme

Hi,

I have a localization question.

I am currently building a child theme base on the Hybrid parent theme, which is localized, that is hybrid > languages > hybrid-fr_FR.mo exists.

But there are some strings that I want to overwrite in my child theme. Ex. I want to replace the Search this site… Rechercher sur ce site… string by Search this blog… Rechercher dans ce blogue… (Yes, I excluded my pages from the search capacity).

Now, I could directly edit this file, but since this is a parent theme, it would be overwritten during an update.

I want to make my [child theme folder] > languages > fr_FR.po or should I say .mo file to have precedence over the file in the parent theme.

I can I do this?

Thanks

Pat