I would figure out why you have babies that are refusing to eat, then worry about breeding..

Can't say I've ever heard of babies 300-600g not eating unless there were problems. They should be pounding food, regardless of if they are male or female.

If the female is dark, put the het Pied with her, if she's lighter/golden, put the Pastel with her(if the Pastel is actually decent looking and doesn't look like a light normal).