As I stated in my posting, it would be primarily based on the geneological evidence and the secondary to this would be if he presented his case to the clan and the clan supported his "application" to the Lord Lyon.
Now how would this election take place? I would not neccessarily call it an election, but a general consensus to his application.... All roads must be through the Lyon Court, which under a fair consideration, made by the facts presented.. Granted the application is only speculation and I have no support, one way or another, other than an interest of watching the events unfold, and the results, whatever they may be..