Assume that I have a specific Excel workbook that will ALWAYS be open. I simply want a VBA code that will activate the ALREADY-OPEN excel workbook from Word and then run an Excel macro.

I currently have one that will RE-OPEN the excel document and run the code but I only want it to ACTIVATE IT, not reopen.

Here's the code I have:
Set oExcel = New Excel.Application
Set oWB = oExcel.Workbooks.Open("P:\For Ken\OSTEEN POSTAL CALCS\99 - OSTEEN POSTAL CALC.xlsm")
oExcel.Visible = True
oWB.Application.Run "Module10.PASTE_FROM_WORD"
This will REOPEN the excel workbook even if it is already open...which, as stated, I DON'T want to do. Any help? Seems like it would be pretty straightforward but the stuff I've found on the 'net is ruh-diculous!