How to help my granddaughter avoid what I had to go through

I am starting to see signs of ADD in my 4-year-old granddaughter whose parents both have ADD/ADHD. I know it is too early yet to get her diagnosed, and she certainly doesn't need to be on medication yet, but I would like to spare her some of the agonies both her parents and myself have had to live with growing up with ADD. She is impulsive, wants what she wants "right now", craves constant attention, and can hyper-focus when she likes something. Many of the things I see may be just being 4, but I believe her chances of not having ADD are slim, due to her family background. How can I channel her impulsivity in a good way, without losing her spontaneous nature and creativity? Her mom is a wonderful, warm and loving mom who spends lots of time trying to teach GD to use her manners, be a nice person, learn lots of new things. GD is very smart - she can already read a bit, print a bit, and is learning how to add. However, GD's dad (my stepson) has Behaviour Conduct Disorder; has been diagnosed, as well, with Anti-social Personality Disorder, and is a cocaine addict. I want to help GD avoid going down her father's path - what can I do to help?