A previous paper (Kapilakarn, K.; Luyben, W. L. Ind. Eng. Chem. Res. 2003, 42, 1890-1904) explored the design and plantwide control of a continuous process in which two reversible reactions produced two desired products M and D. Because chemical equilibrium established the amounts of the products leaving the reactor, the use of product recycle was required to operate over a range of product ratios W(M + D). This paper extends the previous work to consider the more complex system in which there are three reactions producing components M, D, and T. Desired product ratios can span the entire ternary distribution space (M/D/T), depending on market conditions. Both steady-state design and dynamic control are explored for this three-product process, which features one reactor, four distillation columns, and two recycle streams. Several conventional control structures are studied in which the flow rates of the fresh feed streams are fixed or manipulated by level or composition/temperature controllers and the production rates are not directly set. An alternative "on-demand" control structure for "agile" manufacturing is also developed in which all three product streams are flow-controlled. The control system adjusts the conditions in the plant and the fresh feed streams to achieve the set product flow rates. This control structure requires no reactor composition measurement. The ratio of the fresh feeds is adjusted to give the desired production rates of M and T, and the recycles of D and T are adjusted to give the desired production rate of D. Appropriate liquid levels in the process are used as feedback information to trim the fresh feed ratio so that reaction stoichiometry is precisely satisfied.