How to change source and target language of a .sdlxliff file

HI all

I have a Word file with texts in 2 source languages, EN and DE.

EN must be translated in FR and DE must be translated in ES.

The first step (EN to FR) has been completed and now DE must be translated in ES.

Instead of return to the Word format, I'd like to use directly the .sdlxliff file (which now contains FR and DE) but it seems impossible to change the source and target languages of the .sdlxliff  file.

Does anybody now a solution?

Thanks