To UnMerge a range of cells, you have to add a small piece of code. Here are the steps to achieve un-merging of cells.
Take a copy of the existing Excel VBO and name it myExcel VBO. Open the myExcel VBO and right click on 'Select' object and choose 'Duplicate' from mouse menu. On Name new page pop-up, give a name as Select - UnMerge and click OK. Now, this will create a new object, Select - UnMerge in myExcel VBO. Do not forget to publish the new object Select - UnMerge.
On the 'Select - UnMerge' double-click on the 'Select Cells' Code Stage and change the name to 'Select Cells - Unmerge' (to avoid duplicate name error). Go to Code tab and add the below line after range.Select() line
sheet.Range(Reference).UnMerge()
Click on Ok and Save the myExcel VBO object.
Now, you are ready with the code changes to unmerge the cells.
In your Process add an action, Select - UnMerge from myExcel VBO with inputs- Handle, Workbook, worksheet & Reference. For input Reference, pass the merge cells range, example "A1:A3". On executing the action, it will un-merge the cells.
Note: Entire Process should call myExcel VBO instead of Excel VBO, else you will run in to exceptions if you try to use only one action from myExcel VBO and have all other actions calling Excel VBO.
Post back, how it goes.