I have been involved in several estates, on both sides of the issue. I have been the executor in two estates. If the lawyer did a good job on the wills the challenges usually are not too big of an issue. Also I have noticed those making the most noise are the ones with the fewest assets.
We are lucky here. The local probate judge's family is in the law business. People have found out real quick that they do the good wills in this county. They are good. They have the bigger estate wills signed by the three county court judges as witnesses. That really has stopped the nuisance type suits over those wills.
My lawyer wrote my will. Then he turned it over to them to look over. When it was all correct I went to the court house and walked the will through the three judges chambers. We all signed the documents right there.
Tell her that she should be fine. Think of the good times with her Father. Tell her she did what was best for him in his later years. That is the real important thing. The money is a side issue. You will not stand before God with your pockets full of money. Her taking care of her Dad will be what is important.