When I was young, my mother used to massage coconut oil into my scalp and hair shafts after shampooing and I had really thick, healthy, lustrous hair. Of course, as I grew older, this practice ceased and I discovered commercial shampoo and conditioner, which left my hair in an abominable state. Recently though, I've discovered Chagrin Valley Craft soaps and 'poo bars (http://www.chagrinvalleysoapandcraft.com) which in conjunction with herbal vinegar rinses have left my hair soft and shiny again! Might be a little too harsh for your granddaughter though, so I recommend just going with coconut oil (or monoi). It's tough to wash off though, so unless it's a daily treatment, don't use too much, but work it in well. You could also mix it with some jojoba. Some others have had good results with shea butter - whipped shea would be easier to apply than solid shea.