One of the hardest questions of stellar pulsation theory is the modal selection in multi-mode oscillations. Linear stability analyses predicts a dense spectrum of excited modes; however, the amplitude of these modes cannot be determined by these calculations. Only nonlinear hydrodynamic models can answer the above question; however, codes exist only for radial pulsations. Amplitude-equation formalism works well for predicting and understanding the results of radial hydrocodes. We extend our results of double mode pulsations for the interaction of dozens of modes and check the possible scenarios in multi-mode oscillations.