Single necessary and sufficient stability conditions, are presented, for a common Linear Time-Invariant (LTI) controller that simultaneously stabilizes each of a given family of LTI plants. It is assumed that the strictly proper, lumped and LTI plants have stabilizable realizations and are strongly stabilizable, and that the state-space dimensions of the plants do not change, are even and are double the input-space dimensions of the plants. The stabilizing controller is designed for a nominal plant and its free parameter is fixed assuring stability for all the plants, and assuring a stable controller. The stability conditions for simultaneous stabilization are based on the parity interlacing property, on a matrix that must be unimodular and on an analytical expression of the stabilizing controllers.