Hi Nakata,
Thank you very much for using syncfusion products.
Yes it is possible to create add-ins using Syncfusion XlsIO. The following code snippet explains you how to create the add-ins using our XlsIO.
Code Snippet (c#):
IAddInFunctions functions = workbook.AddInFunctions;
functions.Add(@"C:\Documents and Settings\ Administrator\Application Data\Microsoft\AddIns\Discounts.xla", "discount"); sheet.Range["A3"].Formula = "discount(A1,A2)";
I have also attached the sample tested at our side along with this update. Please try this at your side and let us know whether this helps you.
Please let us know if you have any clarifications.
Thanks,
Jawahar.
Sample_c1bc63b9.zip