Can I mix cow's milk in my baby's formula?

yes you can but please only if your baby is at least 1 year or more. the thing with cow's milk is that it can cause a lot of digestive issues in some babies and lead to gas. also, some babies are allergic and may develop severe constipation after having cow's milk. if you still want to try, start with very small amount and see how your baby reacts to it.