Baby #4 has pink eyes so you have a Lutino. Genetically, the baby is a female. Your hen doesn't show the ino coloring so dad is the one carrying the gene. That being the case, any and all pink eyed babies are females. No DNA sexing necessary.
Ino is a sex linked mutation so you only need the gene on one side (dad) to produce a visual ino. If mom is the ino and dad isn't carrying the ino gene, all males will inherit ino but none of the babies will show it.
Since mom and dad are doing such a good job with the babies, have you considered co-parenting instead of pulling the babies to hand feed? Just socializing is a lot more fun and you don't have the responsibility of working your schedule around the feeding schedule for the babies.