Multiple graphs in same canvas without repainting

Hello,
I have a problem when plotting multiple graphs in the same canvas. I define a canvas and divide it in several pads. Then I define ONE TGraph object which is used in a loop to fill the different pads. So in the loop the same TGraph object is used to make different graphs.
Till now everything goes well, but if I change one of the pads, for example I make a fit, all they others are repainted and become identical to the one I changed. Do you know how to avoid this?

Thanks,
Bob

see TGraph::DrawGraph

Rene