In an earlier article of the authors, the rectification body method was introduced for rapidly calculating the minimum reflux of nonideal and azeotropic multicomponent separations. Here, the RBM is generalized to two important classes of complex columns: (1) columns having sidestreams, and (2) columns with one or several side-enricher and/or side-stripper columns. As in the case of simple columns, the method is entirely general and does not require any a priori information on the limiting pinches prevailing in the various column sections.