This is dead in the water. According the article, "[t]he group proposes that the shared UK functions would include the monarchy as head of state, foreign affairs, defence, national security, immigration, international treaties..." The reason that Scotland apparently wants out is they want to remain in the EU. To do so, Scotland would need to be able to have its own international treaties. It can't share the power to make international treaties with this new proposed union and remain in the EU.
This is dead in the water. According the article, "[t]he group proposes that the shared UK functions would include the monarchy as head of state, foreign affairs, defence, national security, immigration, international treaties..." The reason that Scotland apparently wants out is they want to remain in the EU. To do so, Scotland would need to be able to have its own international treaties. It can't share the power to make international treaties with this new proposed union and remain in the EU.