Hi,
It’s important to start feeding extra foods when you first put up the nest box. The parents need to be used to eating these foods. If you have only been feeding seeds, then they chicks may not survive. The parents need to be eating a nutritionally balanced diet like pellets. In addition, offer leafy greens, veggies, some fruit and an egg food. This can be a dry commercial egg food, or you can cook an egg, with the shell washed, crushed and cooked with it. Off all of these foods daily in large amounts, and refresh the food and fresh water several times a day as needed.
Thank you for asking Lafeber,
Brenda