Assigning variable to open workbook

[DavidBW]

Hello

I want to create a report that pulls in data from a shared workbook containing multiple worksheets.
Unfortunately I'm stumbling fairly early as I can't set the variable to refer back to the original file containing the data once it has been opened. Basically I need to be able to toggle between two workbooks but the name of one will vary every time it is used to create the report. Code is as follows:

Sub ReportMacro()
Dim fNameAndPath As Variant
Dim THISWB As Workbook

'Step 1

fNameAndPath = Application.GetOpenFilename(FileFilter:="Excel Files (*.XLS), *.XLS", Title:="Select File To Be Opened")
If fNameAndPath = False Then Exit Sub
Workbooks.Open Filename:=fNameAndPath

Set THISWB = ActiveWorkbook

On Error Resume Next


Dim WB As Workbook
WB = "FSD BAS report test.xls"

'
    Windows(THISWB).Activate
    Sheets("Core Input").Select
    Range("I8").Select
    Application.CutCopyMode = False
    Selection.Copy
   
    Windows(WB).Activate
    Range("A3").Select
   
    Selection.PasteSpecial Paste:=xlPasteValues, Operation:=xlNone, SkipBlanks _
        :=False, Transpose:=False
    
    Windows(THISWB).Select

Works OK to this point but doesn't go back to file opened at step 1 above but stays in current as this is now deemed to be the active workbook


Thanks in anticipation