VBA - Combine Tables to Add Unique Rows - excel

Question

I have a workbook that is being updated regularly by third parties. Let's call each update WB1, WB2... The data in WB is formatted as a table in columns A:F, and there are approx. 2000 rows. There is one sheet of data. In my copy of WB, I called it "Master." In WB1, WB2..., it is "Indexes." Column A has a unique identifier for each row, and the rest of the data is text.
I'm adding notes next to each row, in columns G:H. I need to be able to merge the unique entries from WB 1 into my copy of WB, while preserving my notes in G:H, and the conditional formatting I added to WB. I want to use VBA, and I do not have Microsoft Access.
I found a partial solution here: Find Duplicate Values In Excel and Export Rows to another sheet using VBA
I made the following changes to the solution linked above:
Option Explicit
Sub MergeTables()
Dim wstSource As Worksheet, _
wstOutput As Worksheet
Dim rngMyData As Range, _
helperRng As Range, _
unionRng As Range
Dim i As Long, iOld As Long
Set wstSource = Worksheets("Indexes")
Set wstOutput = Worksheets("Master")
Application.ScreenUpdating = False
Application.Calculation = xlCalculationManual
With wstSource
Set rngMyData = .Range("A1:J" & .Range("A" & .Rows.Count).End(xlUp).Row)
End With
With rngMyData
Set helperRng = .Offset(, rngMyData.Columns.Count - 1).Resize(, 1)
Set unionRng = .Cells(3000, 3000) 'set a "helper" cell to be used with Union method, to prevent it from failing the first time
End With
With helperRng
.FormulaR1C1 = "=row()" 'mark rows with ad ascending number (its own row number)
.Value = .Value
End With
With rngMyData.Resize(, rngMyData.Columns.Count + 1) 'enclose "helper" column
i = .Rows(1).Row 'start loop from data first row
Do While i < .Rows(.Rows.Count).Row
iOld = i 'set current row as starting row
Do While .Cells(iOld + 1, 1) = .Cells(iOld, 1) 'loop till first cell with different value
iOld = iOld + 1
Loop
If iOld - i = 0 Then Set unionRng = Union(unionRng, .Cells(i, 1).Resize(iOld - i + 1)) 'if more than one cell found with "current" value, then add them to "UnionRng" range
i = iOld + 1
Loop
Intersect(unionRng, rngMyData).Range("A:F").Copy Destination:=wstOutput.Cells(1, 1) 'get rid of the "helper" cell via Intersect method
wstOutput.Columns(helperRng.Column).Clear 'delete "Helper" column pasted in wstOutput sheet
.Sort key1:=.Columns(6), Order1:=xlAscending, Orientation:=xlTopToBottom, Header:=xlYes ' sort data in wstSource back
End With
helperRng.Clear 'delete "helper" column, not needed anymore
Application.Calculation = xlCalculationAutomatic
Application.ScreenUpdating = True
End Sub
This macro successfully adds in the new rows, but my notes in G:H do not line up with the original data anymore.
Can you please suggest alternative approaches, or revisions to this macro?
Thanks
Edit 1:
#dwirony I've attached three photos: A sample version of WB before using the macro, a sample of an updated WB1, and a sample version of WB after using the macro.