Hello, I just wanted to ask, how to make a baby with a real player? I seached everywhere, but I dont know how.

For the 1.12.2 version 6.0.0 and higher use the command /mca help to show all mca commands. The command to propose with the player is /mca propose and to have children use /mca procreate.

There is currently a bug right now allowing you to only have 1 child with a player.