All recommended feeding guidelines are just that: guidelines for the average dog. An "average" means there are always those who are outside the average (on both sides). All types of feeding should be done as "feeding to condition" - in other words, start with the guidelines for whichever food you're feeding - then adjust according to how your dog's body feels to you. If your dog feels too bony and you're feeding NV, then I'd probably feed an add'l 1/4 medallion at each meal and wait 2-3 weeks, and adjust from there.
Personally, I wouldn't feed milk if a dog was a bit skinny - I'd feed it food.
