Caiowulf

Hi. I looked everywhere and tried several times but I can't do this. I want to create a Cup in my country for Youth teams. Mimicking the National Cup but for all Reserve Teams and U20 teams. I have created several competitions and leagues and youth teams competitions, but I cannot do it this way. What I want to have is like a FA Cup but played only with U20 teams. I mean, still having the national cup and adding this new cup for youths. Is there a tutorial, article, post or video I can follow to understand what am I doing wrong? When creating cups I have no options to set them for youth teams and when creating youth competitions I can only do them per division (Cup or League), not a national one.