Settlor left the residue of her estate in trust, with her brother, sister, and two nephews as income beneficiaries. The nephews were given a special power of appointment with respect to their wives and issue. This special power was further limited in that only income could be appointed to the wife. One of the nephews died unmarried and without issue. The other nephew, Cabot Morse, who had a wife and a son from a prior marriage, exercised his power of appointment over the trust income in favor of his wife. However, he did not exercise his power with respect to the principal, and his will clearly expressed his intent not to exercise it in favor of his son, Cabot Morse, Jr. Cabot Morse, Jr. predeceased his father. Settlor further provided that, if neither nephew exercised his power, the trust assets were to be distributed to certain charities (D). In earlier actions, the court determined that Cabot Morse's exercise of his power over the trust income in favor of his wife was valid, notwithstanding the fact that he failed to exercise the power with respect to the principal; and that D had no interest in the trust funds, despite the fact that neither nephew fully exercised his power, since Settlor's clear intent was to keep the trust property in her family. The trustees (P) filed the present action after the death of Cabot Morse's wife, to determine how the principal should be distributed.