Section 9(9)(a) in The Maharashtra Employees of Private Schools (Conditions of Service) Rules, 1981
(a)In case it is not possible to fill in the teaching post for which a vacancy is reserved for a person belonging to a particular category of Backward Classes, the post may be filled in by selecting a candidate from the other remaining categories in the order specified in sub-rule (7) and if no person from any of the categories is available, the post may be filled in temporarily on an year to year basis by a candidate not belonging to the Backward Classes.