LOL, I just realized a way that I can relocate a liberatable faction which block my trade path to another region without breaking protectorates.
For example, in this one, I play as Prussia and I liberated almost all minor factions so far. And Hanover blocks the trade path to Oldenburg, Holland and Westphalia.
I gift Normandie to Hanover and a region next to Hanover to a warring major faction. After a few rounds, that major faction will capture Hanover making Normandie the capital of Hanover. :D:steamhappy: Then I can recapture Hanover and I can trade with all factions nearby and Normandie Hanover as well, because Normandie has a port.