Hi C.,
What a great sister you are being.
I hear this all the time, have her stop using the baby oil immediately. Mineral Oil (baby oil) is an occlusive oil which seals the skin. It is a petroleum product, yup 7 times refined motor oil, yuck! Great for your car, not so great for your skin. If she googles it she will never put it on anyones skin again. I'm not sure what Aquaphor is but it is always a good idea to check the ingredients first as even doctors aren't always aware of the dangers of some ingredients.
Arbonne makes a baby care line which takes care of all kinds of skin issues. The baby hair and body wash works great and is made from plants so you don't have to worry about harming the skin. They also have a baby oil, baby lotion, diaper rash cream and a spf 30 sunscreen available.
If she wants to know how to get some let me know and I will get you the information for a free sample or at least the website to check out. It would be sent straight to her home so she doesn't have to leave the house to shop.
I hope I've helped a bit.