I managed to locate the information at the Division Scolaire Franco-Manitobaine (of course). Looks like you either have to have French as a first language, or have been instructed for at least four years in French, to go to a Francophone school in Manitoba. So a kid with no French at all couldn't do it - quite understandably, since the other kids in that school would have learned French right from the womb - but if you lived in Quebec for some years and your kid went to French school there, or if you had them in a private school where they taught in French, then they could go there.
They do, in Manitoba, have a 50/50 program where some classes are taught in French, some in English, resulting in a 50/50 split, and any kid can enroll in that program. Mind you, they have similar programs in Ukrainian and German, too.
