David and Alexis, both 28, are interested in saving for the college education of their twin daughters Alie and Amber. They decide to purchase some Series EE U.S. savings bonds because they know that the interest on the bonds is tax-free in certain circumstances. To easily keep track of the savings for each child, they purchase half of the bonds in the names of David and Alie and the other half in the names of David and Amber. Assuming that current tax law does not change, under what circumstances will David and Alexis be permitted to exclude interest on redemption of these bonds?