Copy the new data
Click on Chart
Use menu item Edit | Paste Special and in the dialog stipulate New Series
Indicate if data is in rows or columns (Excel generally gets this right)
Click OK

Note you can select just the y-values, or both x- and y-values. In the
latter case, you need to specify in the Paste Special dialog that the first
column (row) holds x-values
best wishes
--
Bernard V Liengme
Microsoft Excel MVP
www.stfx.ca/people/bliengme
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"M Higgins" <M wrote in message
...
Can you add a new set of data to an existing chart?