chick refuses to eat

Hi all, I'm new to the forum and to cockatiel breeding. We were given 2 tiels and they have decided to mate and lay, so here I am with 4 babies. I've spent the last few weeks reading up on everything chick related. They are being fed by the parents and the two oldest are doing well, the third...

Today I been to the pet market, I saw a baby cockatiel being plucked by his parents, I felt so sorry for the baby, the owner sold it to me for a very cheap price because he couldn't raise it up himself and he didn't want to separate him from his parents ! So I just took it back home.. I knew...