Need help with tiny fix for Chilean Cup

[m.braathen]

Hi! In the game, the Chilean cup final is played in two stages, both on neutral ground. I need to change this to home and away, like in real life. I know how to change this in the editor, but when I try to verify the rules, it just says there are too many teams (18 instead of 16) in the league. I know it's because the league is going from 18 to 16 teams by 2022 or whatever.

I didn't change any other rules, only that the cup final should be played at home and away. How can I get past this error of wrong amount of teams?