there is no way to load an existing xlsx file in flutter with the package syncfusion_flutter_xlsio

[amincoding]

there is no way to load an existing xlsx file in flutter
i have worked allot on the file, and then when i wanted to start using the woorksheets to save them all in one file, i didnt find i single way to load ur previously exsitsing file and add worksheets to it

[PandikumarDuraivel]

Unfortunately, we don't have support for your requirement. And, we don’t have any immediate plan to implement this support.

You can track status of the feature through this link:
https://www.syncfusion.com/feedback/21974/read-excel-files-using-flutter-xlsio