Thanks everyone for your input. I ended up calling the Virginia Department of Taxation customer service line (https://www.tax.virginia.gov/contact-us). The answer from the agent I talked with was that only the owner of the account may claim a deduction and only for contributions that they make.
If someone makes a contribution to an account they do not own, no one can take any deduction on that contribution.
In my scenario, my brother making a contribution to an account with my daughter of the beneficiary, for my brother to be able to get the deduction he would have to set up a new account with him as the owner and my daughter as the beneficiary.
