If variable range is > 3 than do action else do other action

Some background: Each month I build a pivot table that has approx 30 or so business units (along the y axis) - lets call them groups. Each group has a number of GL accounts that change month to month. For example, Group 14 might have 10 GL accounts one month than the next have only 3. For each group, we need the summation of the totals for the GL accounts (that start with PL203000 & PL211010) for each group. Before we had to total these GL accounts for each group by hand. This has been solved with the code I have displayed below.

The code works perfectly when each group has more than one GL account (See pic 1)

The problem I am facing is when there is only one GL account, the code doesn't sum the correct amounts (see 2nd pic).

When digging into my code, you can see that it is summing the incorrect sections since i have a Rows.Count.End(xlUp) establishing the range. If there is only one GL account, it skips to the next section thereby establishing an incorrect formula

Perhaps my code needs to be completely revamped in order to account for groups where there is only one GL account to sum? If so, what sort of if statement can i code where it ignores groups that have only one GL account?

If not, than is the solution to have VBA count the range and if it is less than 3, ignore group and move on to the next?

'this section spits out the values needed to sum
For i = nRowMax To 4 Step -1
If Left(Cells(i, 1), 8) = "PL211010" Or Left(Cells(i, 1), 8) = "PL203000" 
Then
        Cells(i, 4).Copy
        Cells(i, 5).PasteSpecial xlPasteValues

        Range(Cells(i, 1), Cells(i, 4)).Select
        With Selection.Interior
            .Pattern = xlSolid
            .PatternColorIndex = xlAutomatic
            .Color = 65535
            .TintAndShade = 0
            .PatternTintAndShade = 0
        End With
End If
Next i
Application.CutCopyMode = False


'this section uses the values the first section specified to write the sum formula
'i believe the macro uses this section of code to write the first formula and the next section of code writes the formulas for the rest of the groups
Dim firstRow As Variant
Dim finalRow As Variant
    finalRow = Range("E" & Rows.Count).End(xlUp).Row
    firstRow = Cells(finalRow, 5).End(xlUp).Row
    If IsNumeric(Cells(finalRow + 1, 5)) Then
        Cells(firstRow, 6).Formula = "=SUM(D" & firstRow & ":D" & finalRow  & ")"
End If

'this section goes through the whole sheet to sum each group
For y = firstRow To 5 Step -1
finalRow = Cells(y, 5).End(xlUp).Row
firstRow = Cells(finalRow, 5).End(xlUp).Row
If firstRow < 5 Then firstRow = 5
If IsNumeric(Cells(finalRow + 1, 5)) Then
    Cells(firstRow, 6).Formula = "=SUM(D" & firstRow & ":D" & finalRow &")"
End If
y = firstRow
'If firstRow = 5 Then Exit Sub
Next y