I know, I am also really close. I have reduced my stutter by 90% (in good times I have almost no stutter for months), but having the goal of complete fluency will only get you frustrated / irritated and not help your progress. For your sister: only if your sister herself wants to improve her speech, she should do something about it. If she is ok with it and enjoys her life, why do you want her to do somethign about it? It should really be an intrinsic motivation. The techniques learned to overcoe stuttering can be split up in physical techniques (diaphragmatic breathing, speaking slower, etc) and physcological techniques (how to handle anxiety, disclose to people you stutter etc). Since your sister doesnt have social anxiety, sounds like she would benefit most from the physical techniques. However I think all stutterers will benefit from both.