Quick VBA Macro to group rows based on cell values - Outline Style

[Dedonovan]

Hi Everyone,
I'm attempting to reengineer a similar post about grouping columns but I want to group rows. Below is the original thread with an excellent response from @Crystalyzer:
Group by Column Thread

What I want to do is group rows of sub-accounts within a parent subtotal row and Grand Total. Below is what I would like the final output to look like. Starting point is identical without the groups.

This is the current code I have so far that loops through the rows and appears to identify the correct Subtotal rows but doesn't group the rows. I appreciate any help. Thank you to @Crystalyzer for getting me this far.

Sub GroupRows()
    Dim i As Long, grpRowStart As Long, grpRowEnd As Long
    Dim strtRow As Long, endRow As Long
 
    If Range("B2") = "" Then
        strtRow = Range("B2").End(xlDown)
    Else
        strtRow = 1
    End If
 
    endCol = Cells(Rows.Count, "B").End(xlUp).Row

     
    For i = strtRow To endRow
        If InStr(2, Cells(i, 2), "F_6") = 0 Then
            If grpRowStart = 0 Then grpRowStart = i
            grpRowEnd = i
        Else
            If grpRowStart <> 0 And grpRowEnd <> 0 Then
                Range(Cells(grpRowStart, 2), Cells(grpRowEnd, 2)).Rows.Group
                grpRowStart = 0
                grpRowEnd = 0
            End If
        End If
     
    Next

End Sub

Thanks in advance for any input!!