Welcome...
Please be sure to ask many questions about hand-feeding your babies, and about housing them...I'm a longtime breeder, and there are so many little mistakes that can make your babies sick or worse, I hope you have done much research before taking this on...
Important questions for you:
Are you using a candy/cooking thermometer to make sure that all formula you feed them is between 104 and 110 degrees F?
Are you keeping them in a proper Brooder at all times so that their ambient air temperature is at 95 degrees F?
How many times a day are you feeding them right now? Are you checking their crops BEFORE AND AFTER each feeding, first to make sure they are almost empty, and then after to make sure they are full enough? Are their crops fully emptying overnight?
Are you weighing them with a digital kitchen scale every day to make sure they are gaining weight?
Do you know the proper method to actually hand-feed them with a syringe/eye-dropper? Are you going in from their left-side, over and across the tongue, and aiming towards their right-side of the back of their throats?
*****Please be accurate about both the formula temperature and their ambient temperature...If the formula is 1 DEGREE too cold they can quickly develop a bacterial or fungal infection throughout their GI Tracts and Crops. 1 DEGREE too hot and it will burn their crops, causing a horrible wound and following infection...And if they are not staying in a Brooder or a homemade Brooder that keeps them at 95 degrees before they grow-in all of their down feathers, and then at 85 degrees after that, until they grow in all their proper feathers, once again, they will not be able to properly digest their formula and will develop a horrible bacterial or fungal infection throughout their GI Tract, Slow Crop, Crop Stasis, etc.
Please feel free to ask any and ALL questions you may have..Not many people without experience take-on hand-feeding baby birds and are successful at it, unfortunately, so please be slow, careful, and always ask questions...