Yeah , i tested different things , editing the save , but those vassals wouldn't move it to NA even given 8 provinces with cores and culture , etc (and them removed from HRE)
I have a few days to imagine a scheme to get one vassal to relocate there , like Portugal often does if they are reduced to Lisboa.
selling a province to Malacca or any non-european country so they won't change the culture, won't allow me to sponsor nationalists , only patriots , so this don't work either.
Once they have accepted one, they will have very likely to recieve other provinces adjacent.