Merlin, I am glad you have clarified some of your point of view.
I understand your argument about the current Queen as Head of the Commonwealth, but that, I think has nothing to do with a nation (in this case potentially an independent Scotland) seeking to have the same monarch as England and to have separate coronations.
It seems to me that in saying, "James I was King of Scotland many years before he became King of England, hence his coronation at Westminster in 1603. Charles II succeeded to the Throne in 1649 when it wasn't possible to have his coronation at Westminster, which took place in 1661, after the Restoration", you are suggesting that a Coronation by the Church of England, in England is somehow superior to a Scottish coronation.
How can that be so? Obviously James VI/I and Charles II had both been through religious coronations prior to their coronation in England. If we followed what I think is your point of view, then there would not have been any need for those Kings to have a second coronation in England. Nevertheless, I think that politically it would have been disastrous if those Kings didn't have an English coronation.
Why would a second coronation be considered "potentially blasphemous"?