Trendline in a Chart Question

[ExcelHELP!]

Hello! I have a question about trendlines in scatter plots:

I would like to add new data to my chart without changing the already existing trendline. Any suggestions?

 

[Dimli]

Right click on the chart, select Source data, Series, then Add.
Select the range of new data that you want to include.
This new range will not change your existing trendline and will even allow a trendline to produced from the new data.

I hope this helps