I wouldn't write anything until you're ready to negotiate, accept or withdraw. I never responded to a school after acceptance and scholarship offer and then they randomly gave me an unsolicited increase from $15k/yr to $25k/yr.
@lsatings Congratulations on an amazing opportunity! I have so much respect for you and your deliberate evaluation about your future. As a mom of daughters not far behind you in age, I would hope they would seize such an opportunity without regrets to ...