True physical meaning of varactor in series feedback oscillator.

In series feedback oscillator we can add varactor to tune frequency. Is it true that adding a varactor with some reverse voltage just changes reflection coefficient of matching network? As if it were designed for other frequency... So i can analyze each state without varactor and just a capacitor? For example, analyze 100 points over voltage range in simulation program, only changing capacitor value, drawing reflection coefficient and stability factor to see if it can oscillate through full range of voltages.