Sometimes, when they are little, they get soooo busy that they dont realize that they have to go potty and end up with an accident. I know when my son was 3, and I didnt have any other kids around, he would do this, even in public. He would basically just forget because he was sooo busy. Its hard having a baby around and a young one who can divert back just as easy. The one big suggestion I have to basically a reward system too. When the baby is sleeping or napping, and she hasnt had an accident, play a game with her that really is out there, like a dress up tea party, with milk or water to drink and something to nibble on. I dont know if you have any dress up clothes, but just putting on really nice clothes will work. Set it up some dolls or stuffed animals to have it too. It doesnt have to be a tea party, it can be anything you enjoyed as a child or whatever. I hope this helps, Good Luck!