It's so funny what happens when you put your mind to it. I told my Mom what's going on and she's been on a mission. She's spoken to our old vet AND a Merrick representative.
Really, there's very little difference between Merrick's All Life Stages and their Puppy formula. There's 4% (minimum) difference in protein (24% Wildnerness and 28% Puppy) and the rest of the ingredients are really similar too. (Though the puppy formula is a different flavor then the Wilderness blend.)
Her old food, Small Breed Puppy Eukanuba, is 32% minimum of protein. From 32% to 24% seems like a lot, but 28% to 24% isn't that big of a difference. I'm a bit torn. Of the kibble available in the stores here (there's no Mom and Pop good dog food stores, only big chains) Merrick seems like one of the best brands available. So I'm thinking of maybe using Merrick and switching to the Puppy formula (and then back to Wilderness when she's old enough to be on adult food). Though it concerns me that a dog food brand would have an all life stages AND puppy and senior foods.
If a food were good for all life stages why would they have any other versions?