It sounds as though you made the right desicion, hopefully he will find a home more suitable to his needs. You both should go pick out a dog together and maybe let Maggie and Sadie meet the new dog on neutral territory before just bringing a new dog into their space.

Last October we adopted an Aussie from a rescue and he seemed perfect. We visited him for a couple of weeks at the rescue, had a home check and he met our dogs and everything was fine. We finally adopted him and we had Lenny for a month and he started biting my dad in the face and suddenly tried eating our cats, giving him back to the rescue was the hardest thing but we knew he wasn't right for the family. Then 2 months later Jack came into my life totally by accident and it was the best desicion we made! The right dog will pick you when the time is right!