Section 7A(1)(a) in The Bengal Criminal Law Amendment Act, 1925
(a)if after the commencement of a trial by Commissioners under this Act any person surrenders or is arrested who, in the opinion of the [appropriate Government] [Words substituted by the Government of India (Adaptation of Indian Law) Order, 1937.] might, if he had surrendered or been arrested before the commencement of the trial, have been tried jointly with the persons under trial the [appropriate Government] [Words substituted by the Government of India (Adaptation of Indian Law) Order, 1937.] may direct that he shall be placed on his trial jointly with such other persons at the said trial: