What to eat, what to eat....

Resident Dog ... Allie, 10lb Schnauzer, dines on 1/2cup NutroMax Weight Management, twice a day.

Enter New Dog ... Adopted McKenzie, 30lb Mutt(!), according to shelter, ate 2cups of Pedigree once a day.

Shelter gave me a zipper gallon bag of Pedigree, and I scurried out to PetSmart. Settled on Authority regular adult dog food (better quality than the Nutro adult food I saw... less corn & corn gluten).

Since Saturday, McKenzie has hardly eaten. I first fed her in her crate, some of the Pedigree, some of the Authority. No-go. Sunday evening, she ate probably 1cup total feed. Yesterday, she wasn't interested in the morning in her own food, but ate the few pieces of Allie's food that remained. Last night, she ate probably less than 3/4cup of the mix.

This morning, being creative, I gave Allie her food, and offered McKenzie a 1/2cup of Allie's food, 1/2cup Authority. I fed them both in the kitchen, side-by-side, hoping one might motivate the other to finish a meal. Allie scarfed hers up like she hasn't eaten in months (like normal), McKenzie selectively picked Allie's NutroMax out of the bowl, and left the rest.

Any tips? Allie needs the Weight Management to keep her from being pudgy, and while McKenzie is currently at a good weight, I'd like to keep her that way.

Thanks in advance,
-Jennifer, Allie, and McKenzie...