I recommend that your daughter go see her regular doctor
for advice about this issue. It isn't clear how old your daughter is, but depending on her age either her pediatrician
or her regular internal medicine doctor
would be the place to start.
There are many different conditions that can cause fragility and distortion of the nails, which could lead to the kinds of "erosions" that you are describing.
For example, one common skin condition called psoriasis can often cause very significant splitting, pitting, and separation of the nails. Sometimes, this can occur even when other signs of psoriasis (arthritis or red spots on the skin) are not present.
Another common cause of nail changes are fungal infections of the nails. Typically, the nails become quite thickened and yellowed with this condition, which helps to differentiate the infection from other causes, but sometimes the changes can be quite subtle as well.
Trauma to the nails, for example from repeated application of artificial nails, chemical strippers, and manicure products can also sometimes lead to these kinds of nail changes.
Your daughter's doctor will be able to take a better look and help decide what the most likely cause is, and what to do about it.