Are you feeding the parents anything but seeds? You should be giving them leafy greens, chopped veggies, & some fruit. You should also be offering a pelleted food instead of seeds. And most importantly, while they have chicks they need an egg food. It can be a dry commercial egg food or you can cook an egg with the shell washed, crushed and cooked with the egg. You should not stop feeding them what they are used to, but add these foods I have mentioned. The parents need a LOT of food while feeding chicks and you may need to replenish it several times a day.
As for the chick, it’s hard to know if it is OK. I would leave it with the parents and hope for the best. Removing it isn’t a good idea because the chick must be kept at the right temperature. If it gets chilled, the food will not digest and once the food stops moving, the chick will often die. It is better off with the parents and hopefully all will go well.
Thank you for asking Lafeber,