Hi Mark,
Thank you very much for using Syncfusion products.
We have tried the sample at our side to add the new series with the already created scatter chart template and we could see the new series points are shown at the top. We are unable to change the sereis order it has been created and shown automatically for the newly created one at the top.
We have attached the sample for your reference. Please try the sample at your side and let us know if these helps you.
In the sample code at line 32 set the serie.Values=sheet.Range["B2:B11"] then the series shown at the top.
Please let us know if you require any further clarifications.
Thanks,
Sridhar.S
DataSeries-84785_e8c7843b.zip