As a person who’s stammered their whole life the best advice I could give you is to make sure that she’s comfortable with her stammer, as a kid I wish someone told me that it’s okay to be different. It’s also important to talk to her about how she feels about her stammer and how it affects her. Regularly talking about her emotions and attitudes towards her stammer will help her later in life. The last tip is would give you is to build up her confidence. Hope this helps and good luck to you and your daughter.