I am not an attorney but I think what you might be contemplating is very dangerous!
Just for openers, let's say that whatever therapy your friend performs harms a patient. Your company is liable.
Let's say your friend accepts Medicare patients and Medicare has problems with the way your friend is billing. Your company is liable.
Let's say due to her income the company owes more in income taxes. Your company is liable.
Let's say she doesn't pay any bill. Your company is liable.
I can go on and on. You have not told us why she cannot set up her own corporation with her own Tax ID.
I wouldn't go near this situation with a 100 foot pole. This is scary to me
However, once again, I am not an attorney.