advice needed for managing high potential non-regular starters (mostly about B-team and C-teams etc.)

[Feron]

I have just been promoted to the 1st Bundesliga and in this season the number of allowed substitutes apparantly has gone down to 3 again (was 5 in last season). I have signed very promising new players with potential but since I am the underdog now I cannot put them in my first eleven.

For them to benefit from the higher quality (individual) training, I've put them into my first team. And since they are 18 and older, they need playtime. Loaning them out would be a way but I haven't really found good destinations yet. And I'd also rather control their indivual training if that's somehow possible.

I have a U19 (playing in a regular league) and a U21 (not playing in a league) and additionally there is a B-team. 

Is there any way by the way to put my U21 into a regular league or even to found a U23? I have activated the lower leagues in Germany (made them playable) but I still cannot find any option to ask the board.

I really love this game but now at this stage it's becoming tedious to always arrange so many matches for two extra teams and also, they are exactly copying my first team's tactic while I actually was planning to train them in different positions so that I can later switch to a new formation in my first team with them. I cannot change their tactic - this problem seems to be linked to not having delegated their individual training - for whatever strange reason.
Moreover, I have made all of my teams visible on the screen with that extra icon to switch to, but my second team still doesn't have that staff section where you see those "man icons" and that tactic screen to manage.

Generally, how can you give your 19-21 year old very talented players playtime and the best education while they are not good enough for your first team yet? Especially when you are the underdog this season and fear to get relegated. Not being able to substitute them in later in the match with only 3 allowed substitutes makes that pretty hard. Thanks for any help!

Edited April 13, 2022 by Feron