Yes, you can put a little bowl down for them and they'll learn how to drink that way. If they're getting enough liquid from the formula and mush mix, they may not need to drink much, but offer it to them. Can't wait for pictures!
P.S. Purina isn't the greatest food. There are better, premium puppy foods which contain more of what dogs need and less corn and stuff they don't need. And which contain no preservatives and animal products which contain euthanasia drugs. I'd stay clear of Purina. Also, ask your vet about vitamins. Some of the premium foods have vitamins and you want to be careful not to overdose on some of them. So, if you choose another food, show the ingredients to your vet and ask about vitamins. Some good foods are; Chicken Soup for the puppy lovers soul, Canidae, Innova, Natural Balance, California Natural, Wellness. There are others. These you can find at feed stores and pet stores. No food from the grocery store is premium. These premium foods appear to cost more, but there is not the waste as there is with the grocery store brands which are full of fillers, so they eat less. And they are so much more healthy. Good luck!