Do you think DD20 will go to grad school or would you then help DD17 with law school with the extra money? I would maybe have this conversation with DD17 and just say you have been thinking about how she had no incentive to take the merit awards. Does she think it would have changed her choice? And how would she feel if DD20 made that choice? If DD17 says she would not have changed her mind, then you can certainly offer DD20 the new deal. If DD17 says she would have gone to a cheaper school and used the money for law school, it would be hard to change the deal now. I am surprised that question didn’t come up when comparing schools.
One of mine chose the in-state public and the incentive was that he didn’t have to take the federal loans and that we would buy him a car when he was done. The other two had to chose a school that was affordable, but those were still a bit more than the in-state. Loans and no cars for them. But that deal was available to all three.