Not at all... no traitors in these F&I War scenarios
The French can only raise militias on the French population of Canada, so even if they occupy all of the South, they won't get any militia. And conversely for the British when they occupy Canada.
It is a different stroy in the American Revolution scenarios. Both Loyalist and Rebel militias may be raised (even simultaneously) in an area. This is mostly influenced by the presence (or not) of British regular units there and their degree of control of strategic towns.. as a rule, the more the Brits control, the less there will be of Continentals / Militias levies..
Note that leaders with the ability "Patriot" will increase the levy rate by 25% in the favor of their side.
Also each region as a maximum pool of militias in the game, if all are on map, no more are raised.
And, last but not least, in December there is a fair to high chance that militias are dismissed and return home (their enlistment has expired and they are disbanded). Here again, a leader who is "Charismatic" may influence the dismissal rate (less 25%)