I have an existing graph, let's say with 2 series against the x-axis.

In my data table I've just added a new, 3rd column that I want to map to this existing graph. How do I do it quickly? I tried copying/pasting the data column into the graph, didn't work.

Also tried this: right-click graph -> "Select Data" -> Ctrl+click to add a new column to the selection. But this messed up my graph. After adding to the selection, a dialog box pops up with left/right checkboxes, when I click OK some kind of new graph line is inserted. I don't want to replace anything, just add the new column to the graph.