Clotilde R. Keller et al., as Executors of and Trustees under the Will of Adolph Keller, Deceased, Respondents and Appellants, v. Hugo P. Keller, Individually and as Surviving Partner of the Firm of L. H. Keller & Co., and as Executor and Trustee under the Will of Adolph Keller, Deceased, Appellant and Respondent