Using France's french as fallback language when Canada's french does not exist

Hello everyone,
We just installed the "Support" plugin and it's very promising for our needs. We manually downloaded the fr_FR translation and renamed the files to fr_CA so it would work with our WPMU setting (Canadian French), it's virtually the same thing.

Next time that plugin has an update, how can we know there are new strings and if they are translated or not?

Is it possible to automate a fallback from fr_FR to fr_CA when WP is trying to fetch a plugin's translation file?

Thank you for your input!