Abstract: The present paper narrates the influence of nonideality of externally controlled components on multiple-steady-state transitions studied by using the regular solution model. Under certain conditions the splitting of the original cusp causes "twin" bifurcation points accompanied by isolas which could shrink to an elliptic singular point or a cusp, or even collapse to a hyperbolic singular point in the different cases.

Key words: Nonideality, Multiple-steady-states transition, Twin bifurcation, Isolas