http://www.cyh.com/HealthTopics/library/parent _scabies.jpg
scabies tends to run on the feet tummy and hands in the babies I have seen. You should be able to see track marks anbd the parents would most likely get it too.
Ignore Doc and his usual helpful advice. Some people here are useless unless the question is about what pants would you most like to see on Geri Haliwell.
If you have concerns about the little girls care, take it up with them and then if still nothing, go to their doctor yourself. It could be infected Eczema. Tell them to ask for a referral to a dermatologist as she is so young she should get one quickly. Call the health visitor. I know your just the aunty but you obviously care, so take responsibility.