Completely stuck in the game

I've come to the stage in a season with Juventus where I have to register my squad for European competition and i require a minimum of 4 players trained by the club between 15 and 21. I've included my first team, reserves and under 20's in the squad selection and there is a maximum of 3 available. I can't progress in the game or try and negotiate for some old players so unless i'm being naive I have no idea to continue from here. Any help would be appreciated.

Just let it be a place that is open. Register 24 players, then it will for example say (3 +1) players in the field where it says how many you have to register. You can then press register squad and continue the game. Should work,has done it many times myself

Can you not just holiday past it?

Yeah someone else had a similar problem elsewhere after bringing up a championship team to Champs League. Think he holidayed past it

Either holiday or leave a space equal to the number you are short, will both work.

And in future buy more homegrown players haha.

I did just holiday past it in the end, saw no other option. I took this team on so the previous manager obviously had a thing for foreign players