There are no Emergency Subs for Play-offs.
it is not marked in the rules that it is forbidden
You're right. Our mistake.
If there is going to be a new season the rules will get a big update. Some players might agree with me on this one, that there are currently too many "holes" in the rules. I remember always being told "no to emergency subs in playoffs" (even last Season), but thats our mistake if we never wrote it down or specified it.
Coco is hereby accepted as emergency sub, especially because we saw players acting as emergency subs in L1 last week (after the tournament of course).