Devolution can lead to independence, with more powers going to regions. A way to try and prevent this is to split a region that wants to have greater say over it's future and add in regions that have a different cultural history and less support for independence.
Rather than giving Scotland more powers you could split off the highlands to make their own decisions and split the south of Scotland and put them in two different regional governments with parts of north England.
It's harder to build a nationalist party that way and have less nationalism
