Hmmm... I guess i didn't know what i thought i knew. Haha!
So what you're saying is that the the charge on each capacitor remains the same but the potential difference of the capacitors changes; i.e.
Vtotal=V1+V2=q/C1+q/KC2.
So the rule for capacitors in series holds even when a dielectric is...
Two capacitors (lets call them C1 and C2) in series are connected to a voltage source and charged. While still connected to the source one of them is filled with a dielectric (lets say C2 is filled). I know the charge on C2 will change by a factor of K because the source keeps the potential...