Is it possible to build N-push oscillator based on parallel feedback?

In some papers parallel feedback with common resonator and power combiner used to create push-push oscillator for second harmonic generation. All other papers talking abount higher order N-push oscillators use series feedback with common oscillator. Idea is to use several cheap low-frequency active devices to generate high harmonics. The problem is that N-push oscillators output is still low, amplify it is not very good idea because it needs good active device and adds noise. In this paper: http://www.jpier.org/PIERL/pierl34/09.12061108.pdf. Two parallel feedback oscillator combined to create second harmonic, getting more power output than series feedback approach. Is it possible to replace DRO with some kind of ring resonator with N-push lines to center to produce N-push oscillator with more power, than series feedback?