Section 5(2)(a) in The Scheduled Castes and Scheduled Tribes Orders (Amendment) Act, 1976
(a)any locality in a State specified in relation to any caste or tribe in any of the parts of the Schedules to the Orders referred to in the said sections is varied so as to specify a larger area in relation to such caste or tribe, the census authority shall take into account the population figures of the caste or tribe as ascertained in the last census and in any previous census wherein the population figures of the caste or tribe in respect of the increased area had been ascertained and determine the population of that caste or tribe as on the 1st day of April, 1971 by increasing or decreasing such figures by the proportion in which the general population of the State or, as the case may be, the division, district, taluk, tahsil, police station, development block or other territorial division in relation to which such caste or tribe has been specified by the said amendments has increased or decreased between the previous census aforesaid and the last census;