This book from the late 80's/early 90's is about a girl who starts hanging around with another girl who is more wild and left to her own devices, but also has to watch her little sister who she calls "Hairball" (I think). Mild mannered girl also has a little brother. Hairball drags around a ratty stuffed bunny. Wild girl teases Hairball by always telling her that a mean woman and guy named either "rat face or rat boy" are looking for her. Hairball almost gets hit by a train towards the end. No clue who the author is or any other character names and it is driving me nuts!!!!
Forthright, domineering Sara shows Emily how to speak up for herself and what she likes, but as a result Emily finds herself having to take a stand against Sara.