You may have noticed in grand campaign that some nations have colonies Great Britian for the 13 colonies France for Lousiana Spain for New Spain and even the Dutch have some colonies but none of importance here. Simply you need to take out the nations above and the factions will form, Great britian for USA, and Spain For Mexico and Gran Colombia I believe The French being so nice that Canada seriously well Quebec forms in Quebec province.

In the other way around, you need to increase unrest in certain provinces to make a rebellion for a nation to appear. The list goes as
- Quebec
- Greece
- Mexico
- Quebec
- Hungary
- USA
- Afghanistan
- Gran Colombia
- Punjab
- Mamelukes
- Norway
- Scotland
If there are more say in the comments and i will update.
To increase unrest in the province you need to higher the tax and this is a tricky part here. If you don't want your entire nation to rebel it's best to tax exempt the other regions in the same region (forgot name) and only the province that hasn't been tax exempted should rebel and become a nation. NOTE: The nation will be at war with you because it's a rebel state so be sure to try to make peace quick and even make them a protectorate if you can.