Notwithstanding the foregoing sections of this part, if with respect to any gift made pursuant to 7-6.9, the designations of the custodian contains, in substance, the phrase, "until age eighteen", then all records of the custodian with respect to such gift shall contain such phrase, and the gift shall be administered under this part as if the word "eighteen" were substituted for the word "twenty-one" wherever such word appears in paragraphs (a) and (k) of section 7-6.1 and in section 7-6.20.