Thank you all! Today they both were normal, am happy

They were on applesauce added to their main formulae for 24 hours now ( a bit more actually), will gradually be returning to just formulae (as suggested by debbie276 . I kept checking diligently the temp in their box and the crops don't look "forever full", they empty quite well before the next feeding.
We are now around 5 times feeding per day, with 7 hours brake at night). Is that correct? They are asking for food nicely and loudly, but I would not call them greedy though but overall they are active, stretching and flapping the wings. I noticed that they scratch themselves with one of the legs (mostly around the ear area) I would say quite often - can it be mites?
what can I do to prevent the mites in such tiny creatures or they re too young for mites yet? Anyways in general they look well.