Should i get another dog/puppy?? how do i tackle this problem with my other?

Lady need to socializing big time! Butch sound great, sweet dog. Also Lady needs to learn when its her turn to catch or get the ball. My GSD Saber has a favorite squeaky toy which he loves to fetch, as soon as my boyfriend goes to see him he will grab it and to let him know he wants to play. However when Amy, my dads dog came along she was just 3 months old so she wanted to play with him, however its all about training and making sure your dog listens to you, I made Saber sit and lay down and wait his turn, and when Amy brought it back then I told him to get up and get ready and threw it for him. She needs to respect your other dog, Butch.