Not sure
I was under the impression that Vmca and Vmcg was about directional control and not a function of flaps. Vmca and Vmcg are calculated for a value that will allow directional control in the event of an engine failure on the ground (Vmcg) and therefore allow direction control in the event of an RTO. Vmca would allow the aircraft to be controlled in the event of an an engine failure after V1 and the subsequent flight. Vmu is what will change with flap settings as the it decides what the absolute minimum speed for flight will be depending on flap settings, trim settings and C of G.
so the C of G shouldn't make too much difference as long as the aircraft is within its limits of max and min C of G. This isn't a great deal on a DA42 but could be 40-50 tonnes on a B757 or more on the bigger stuff!
I hope this is firstly correct and secondly useful!