Even if Julie took Molly and Daisy to meet a dog at the shelter, they might get along just fine there, and then have issues later when they all got home. There's just really no totally sure way to know how they will get along.

I know when I first moved in with my mother-in-law for a time, Willie was just great, friendly with all dogs, even friendly with Devon... at first.

A few hours later, he got aggressive with him, and decided Devon had to live downstairs. After a few days of working on it, and intervening, they settled again and became the best of friends.