  We present a theoretical scheme for multistability in planar microcavity
exciton-polariton condensates under nonresonant driving. Using an excitation
profile resulting in a spatially patterned condensate, we observe organized
phase locking which can abruptly reorganize as a result of pump induced
instability made possible by nonlinear interactions. For $\pi/2$ symmetric
systems this reorganization can be regarded as a parity transition and is found
to be a fingerprint of multistable regimes existing over a finite range of
excitation strengths. The natural degeneracy of the planar equations of motion
gives rise to parity bifurcation points where the condensate, as a function of
excitation intensity, bifurcates into one of two anisotropic degenerate
solutions. Deterministic transitions between multistable states are made
possible using controlled nonresonant pulses, perturbing the solution from one
attractor to another.
