That should be pretty simple.
- Open your script editor
- Load as many Excel sheets as you want, but make sure that they end up in different tables. To be safe, put the NOCONCATENATE keyword before each LOAD.
- In your document, create as many sheets as necessary
- On each sheet, create a new object to show data from a different internal table.
That's about it. Now, what do you mean by "...stuck with the same file as input..."? Do you want to load multiple sheets from the same Excel? Then change the sheet name at the end of each LOAD statement. You're stuck with the same Excel loading over and over? Use the Table Files... button to explicitly load another Excel.
Otherwise please clarify your last sentence. Thanks.