"Here is our challenge: Most of his family speaks French and the older relatives are unilingual. My family speaks English and they are unilingual.
I've been thinking of a cute pin or flower people can wear if they are bilingual and willing to interpret."I think using a special flower or pin is a great idea, but how to make it even more obvious that someone is bilingual and willing to speak in both languages? I figured why not write a greeting in each language and add it to the flower or pin. It works for men or women enhancing a corsage or boutonniere.
For the purpose of presenting this idea I used a silk flower and a cardstock paper strip to illustrate what I was thinking.
If you want to make this more upscale you could hire a ribbon embossing company to make silk ribbons stamped with the greetings, or you could use fancier paper and rubber stamps with plain or fancy ink to write the words if you're a DIY kind of bride.