Add new source data in graph template

[cylam]

I have applied a graph template to serveral devices, and it worked.

However, after I add a new "line" to the graph template that plots a new data source, the old graphs stop working instantly.

And I try to "edit" the graph of each device, I found that the data source for the new "line" is "None". And I cannot find the new data source entry in the pull down menu.

Worse, I cannot find that data source even after deleting the old graph. It seems I need to deleted the whole DEVICE in order to make the updated graph works.

Is there any suggested way to add new data to old graphs? Thank you very much.