Eriss,
Giving me a link to a picture of a shield is not helpful, because it's not a roundel.
WWII pictures of roundels really only establishes what we already know:
Free French aircraft used at least five different styles of cross, including the main three I posted in a screen print in post #6.
What I would be interested in, is which was the official roundel, if such a thing existed.
At the moment, the only reference to an official aircraft roundel I have, looks like the one in the image below:
I won't change the mod unless I get a decent source showing another roundel was the 'correct' one.
However, post an image of what you'd like it to look like, and perhaps I'll be able to make a personalised roundel for you.
Cross