Is there any possibility to add the youth national teams to the database as well?
Hi - no, there is not. It's much too much work already, we are only a very small team.
If we had 10-20 people working full-time on the database, we would certainly do womens' teams, and maybe youth teams as well. But it's only me working full-time, and some very nice people helping out here and there, and actually dedicating quite a lot of their spare time to this site. For free.