Ineligible after U-19 player appearance

I know it is a stupid question, but...

I play with Rayo (Spanish second league) and in February many players were injured so i called two U-19 players for a game. After a match I send them back to U-19. Next week i found out that my third goalkeeper and one of injured DL are ineligible. ( I know I registered them in the end of January ). I guess U-19 players randomly stole their squad numbers. Since now it is February I can't register them.

1. Or maybe I can? If so - how?

2. (If I can't) - it's normal? Rules are like that?

Thanks.

Have you had those two players registered at the same time with the U19 players? I think that in Spain, only 25 players can be registered at a time.

Have you had those two players registered at the same time with the U19 players? I think that in Spain, only 25 players can be registered at a time.

No. Rule says that all U-19 players can play for first team at any time. So I thought I don't need to waste one of 25 first team numbers registering U-19 players.

But U-19 players don't have squad number, so FM automatically takes them from registered first team players and gives them to U-19 players if they are called for first team. And if that situation happens when registration window is closed, i can't give back number to first team players and they become ineligible.

It's not something simpler, like they've already played for the youth team on the same day you want to play them for the first team is it?

k, I clearly didn't read the first post right. - sorry. (Edit wasn't working)