How can I select the other file to the data partition? When I’ve selected a “Browse for more” the edit app show the list of the worksheet from the main source file. But when I’ve selected a “Select a Source” option, the app asked me the source then I choose Google the app just back to the edit page. So I can’t add more file to the partition.
When you select - browse for more data - you should see a screen like this that will allow you to select a different data source:
Then selecting Google by default should open Google Drive that belongs to app creator’s account where you can pick a different Google Sheet file.