When Lou Lou was in puppy class the trainer said to keep them on a leash when using the come command, that way you can reel them in to get them to understand the command. I am thinking of signing Lou Lou up for the class above the last one to keep us both on track. It takes alot of patience and practice to get it right, you also might want to make sure you work with Coco away from the new puppy so you have her attention! Good luck, she will get there!