Question about the 'add club continental rules' function in FM21 Editor

I'm having trouble with the add club continental rules function in the data editor. I'm trying to edit the number of subs in the champions league, but because I've edited the number of subs in domestic competitions, I cannot access club continental rules. Does anybody know how I can edit the number of subs in the champions league and other continental competitions, particularly after doing so for domestic competitions as it doesn't let you access the club continental rules after that?