[Sigmaplot] - error bars

I am using SigmaPlot to show a multiple line and scatter plot for 4 different experimental conditions. I want to display inter-quartile ranges as error bars, however when doing this the error bars for each line overlap therefore making it difficult to read.

Does anyone know how to stagger or offset the error bars so that they appear next to each other and do not overlap?

I am using SigmaPlot, but I would be willing to transfer my data into Excel if anyone knows a solution there.

Many thanks,