; and (B) ensure that such recipient is enrolled in the loan credit program under section 460, if eligible. (d) Additional administrative provisions (1) Changes to school or designation (A) Change of high-need designation field If a recipient of an initial grant under this subpart has acquired an academic degree, or expertise, in a field that was, at the time of the recipient’s application for that grant, designated as high need in accordance with subsection (b)(1)(C)(viii), but is no longer so designated, the grant recipient may fulfill the service obligation described in subsection (b)(1) by teaching in that field. (B) Change of high-need designation field or school Notwithstanding subsection (b), if a recipient of a grant under this subpart begins teaching at a school described in subsection (b)(1)(B) and in a field described in subsection (b)(1)(C) during the service obligation window, but such school or field later is no longer designated under subsection (b), the grant recipient may fulfill the service obligation described in subsection (b)(1) by continuing to teach in that school and field and completing the required period of service within the service obligation window. (2) Extenuating circumstances The Secretary shall establish, by regulation, categories of extenuating circumstances under which a recipient of a grant under this subpart who is unable to fulfill all or part of the recipient’s service obligation may be excused from fulfilling that portion of the service obligation. (3) Extension of service obligation window The Secretary shall extend the service obligation window of a TEACH grant recipient for a period of not more than 3 additional years, if that recipient has experienced an event described in section 102(a) of the Family and Medical Leave Act of 1993 ( 29 U.S.C. 2612(a) ). 420O. Program period and funding There shall be available to the Secretary to carry out this subpart, from funds not otherwise appropriated, such sums as may be necessary to provide TEACH Grants in accordance with this