Hi Dave_Williams,

Sorry that with the Split Data feature, the data been split would go to a new workbook.

However, you could use the Combine feature to combine all the sheets from different workbooks into one workbook after you apply the Split Data feature. To access the feature, please go to the tab Kutools Plus, in the group Workbooks & Sheets, find Combine. Then click the third option in the pop-up window.
 


You can follow the dialog boxes, or if you need a tutorial, please click here: https://www.extendoffice.com/product/kutools-for-excel/merge-excel-wordbooks.html

If you have any other questions, please don't hesitate to ask me.

Amanda