Food is a very complicated and hotly debated topic when it comes to pets. There are many schools of thought about what is best. If you keep reading on the subject, you won't want to feed a commercially prepared food.
You will want to homecook, which I don't recommend attempting without the guidance of an expert. Or you may decide the raw food feeders have the answers.
There might be some truth to a kibble-only diet contributing to dehydration. I believe this is the case relative to cats, who tend to drink far less water than dogs. Humans obtain a lot of water through food and there is a theory that some hunger signals are really the body saying it is dehydrated. Rather than turn to canned dog food for moisture, I prefer to encourage the boys to drink water and I give them a little fresh food like yogurt, sweet peas, lettuce, and steamed chicken -- but very little so as not to un-balance their diet and cause other problems.
As I wrote to you in the other thread, protein is also hotly debated.
There is no one size fits all perfect answer for what food is best for your pet. Find what works for your little girl and what she will eat consistently and then stick to it. Don't become a rapid food switcher and start offering all kinds of alternatives. You will create a very picky eater and you could create health problems.