Do not understand exactly what do you mean by sentence : "The PIC could switch in 1 of 2 or 3 PLL's for workable operating ranges."
My idea is that PIC should detect the frequency frame in which PPL will be locked.For instance the first frame will be 1 Hz to 20 Hz, the second from 20 Hz to 200 Hz, third from 200 Hz to 2000 Hz, etc.Means PIC will detect the input frequency coming to PIC input pin (and also to PLL) which have to be multiplied by 11, and accordingly will switch the right low pass filter into VCO input.The input frequency will change in value every 5 minutes.
So idea is to switch elements in low pass filter in PLL, not to switch the whole PLL's.