My hair goes horribly greasy if not washed (I wash it every morning before I leave the house).
I tried the Batiste when I couldn't have a proper wash after my op to keep the wounds dry and not being able to bend much and such. Have to say I was impressed! I got a tropical one, got them in Superdrug but got mine cheaper in Savers. I need to try and not wash it daily but I love the lovely fresh clean washed feeling and mine is very fine so quick to dry.
I was going to say the same about massaging the roots, will encourage the oil. Does she use conditioner and, if so, does she use it on the roots? If so then she shouldn't, only use it on the ends.
I love baby shampoo if I want a few gentle washes.