  This work builds upon the recent demonstration of a phononic four-wave mixing
(FWM) pathway mediated by parametric resonance. In such a process, drive tones
f_d1 and f_d2 associated with a specific phonon mode interact such that one of
the drive tones also parametrically excites a second mode at a sub-harmonic
frequency and such interactions result in a frequency comb f_d1/2 +/-
n(f_d1-f_d2 ). However, the specific behaviour associated with the case where
both drive tones can independently excite the sub-harmonic phonon mode has not
been studied or previously described. While it may be possible to expect the
merger of two frequency combs f_d1/2 +/- n(f_d1-f_d2 ) and f_d2/2 +/-
n(f_d1-f_d2 ), this paper indicates that only one of these mechanisms is
selected and also shows an interesting transition linked to this process. Such
frequency transitions from f_d1/2 +/- n(f_d1-f_d2 ) to f_d2/2 +/- n(f_d1-f_d2 )
holds potential promise for computing applications.
