I'm thinking of modding in some events for syndicalist Québec to separate in a mass strike somewhat analogous to the Asbestos Strike of 1949, with the syndicalists taking power after the British Crown orders excessive force. A combination of several independent mutinies in the French-Canadian regiments mobilised to end the strike, the categorical objection (but certainly not mutiny) of some high-up French-Canadians (I'm thinking Ernest Lapointe and Georges Vanier, notably) and hesitation, to say the least, on the part of Mackenzie King, if he's still in power, would allow a coalition of syndicalists, feminists (Thérèse Casgrain being a LWR foreign minister) and communists to take power while the provincial authorities either flee or are thrown out and the army outside of Canada fails to respond in time.
That would have to depend on some things on the part of Canada. The most logical time for this to happen would be shortly after the start of the US civil war, in solidarity to the CSA, but that might imbalance the civil war too much. Syndicalist Québec wouldn't be at war with the US, but would hinder Canada in a fairly serious way, especially if the CSA manage an offensive in Canada.
Otherwise, outrage following the potential defeat of the CSA could trigger the event.
Feedback? Would such events be interesting to "officially" implement? I may or may not bother making events for Québec after independence, I'm not too knowledgeable about the backstory of the whole thing. I expect the French Commune might offer assistance to syndicalist Québec, but it would have to be something nonmilitary unless we want a WWIII to automatically start from this deal, which isn't a good idea. Might give the choice to back them militarily, with 0% AI chance, so players can use it as an excuse to go to war if they really want to.