Remedies for toddler dry hair?

My daughter is 15months old her is on the back is so dry like it won’t even stay down I don’t know if it’s frizzy or dry it just doesn’t look like the rest of her hair in front and sides. I’ve tried kids conditioner, I’ve tried switching shampoos I use mustela now, the only time it seemed to “help” was when I washed her hair with baby oil then with shampoo, some of the oil was still “left behind” and her hair had a “wet” affect the whole day and was soft and down so I assume it just needs moisture in general. Should I keep using the baby oil ?? I mean... when my ends are dry I do use hair oil on myself so you’d think baby oil should be fine or no?

The front of her hair is ABSOLUTELY different silky , soft... is this normal for kids to have different hair types ? Nobody in the family has super dry hair like that so I don’t Know