Originally Posted by
Serb
Unfortunately, you can't invent your own tournaments to tie a player to your football association. It's a friendly and only FIFA / UEFA approved competitions count towards international eligibility.
I wouldn't worry too much to be honest. As far as I'm aware, it would be unprecedented for McCarthy to change his allegiance now that he has been fully capped for Ireland. After everything he went through in Scotland, I'd consider if extremely unlikely that he would swap back to the Scots over being left out of one squad (but subsequently included, yay!).