You said she s 5 1/2 is she not eating hard food becase she has started teething ? What we did with chelsey was mix her hard food with lok warm water. It soften it up .kind of like a soup.. and she liked it that way. Now she is back to hard food but it is the same brand so no issue with the tummy.
Other suggestion you could mix a small amount of the hard food with the soft food.
Mix it very well or she will pick out only the soft food.