For babies that young they are capable of eating hard foods but will still benefit from extra wet food. The key is they need more protien, calcium etc than an adult. Depending what you feed normally it may need some additions to make sure if gives the babies what they need from a dry mix. As well as that i would give them at least one high protien ready meal a day, and possibly have a small mouse sized water bottle or bowl on hand with puppy milk or soy infant formula.
A high protien wet meal is something like;
Egg - scrambled, boiled and shelled, poached, cooked in a bit of rice or other carbs (one egg will do a few meals at this age)
puppy/kitten food - the best are natural ranges as they are less full of rubbish and additives
bird egg food - sold for growing/weaning birds, you make it up into a porridge with warm water or milk (puppy or soya is even better)
chicken - cooked on the bone is best, though it may be a week or two before they take to bones
fish - tinned fish in tomoato sauce or spring water goes down well.
Baby food - 7+ type age groups as it has more substance to it
I would also offer them a pinch of seweed powder on the wet meal about 2-3 times a week (or finley chopped nori sheets sold for sushi making), some salmon oil once a week (or failing that a cod liver oil capsual emptyed onto there food) and offer bones / cuttle bones at least once a week. Add in a small amount of kale or another drak green lefy veg a few times a week (build up slowly).This will help top up some of the key vitamins and minerals that young rats need to grow healthy