so your seniors may be in d1 but your youth team is in d2 or d3
Here's what I had in mind:
Each league would have it's own youth league (I.E. NBBA, NBBA youth league). That way your youth team would face other youth teams of managers in your senior league.
the only flaw is that training doesnt really work with more than 3 players
Honestly, that doesn't concern me, it would get out of control if you could train more than three players (when one position training of course). If you trained three starters for your team, there aren't many other positions that need to be filled and each team should have more than enough money to fill those positions anyways.
There would also have to be some sort of training policy to avoid managers being able to train senior team players along with youth team players. The training limit should be three players max for both senior and/or youth teams.
"You will lose." -Ivan Drago