Match Column A's Project number to change based on greater number in new row

Good day,
the title sound stupid but here it goes.

I have a userform that will change information on my Sheet.

Private Sub CommandButton1_Click()
    Application.EnableEvents = False
    Application.ScreenUpdating = False
    
    ActiveCell.Offset(1, 0).EntireRow.Insert
    Cells(ActiveCell.Row, "N").Value = Cells(ActiveCell.Row, "N").Value & "/T01"
    Cells(ActiveCell.Row, "W").Value = ComboBox4.Value
    
    Cells(ActiveCell.Row + 1, "Y").Value = "hs631"
    Range("A" & ActiveCell.Row + 1).Resize(, 12).Value = Range("A" & ActiveCell.Row).Resize(, 12).Value
    

    Application.EnableEvents = False
    Cells(ActiveCell.Row + 1, "M").Value = Cells(ActiveCell.Row, "M").Value + 1 'THIS is the code I need to modify or add
    


    Cells(ActiveCell.Row + 1, "N").Value = Cells(ActiveCell.Row, "A").Value & "/" & Format(TextBox1, "000") & "/HS"
    Cells(ActiveCell.Row + 1, "P").Value = TextBox5.Value
    Cells(ActiveCell.Row + 1, "Q").Value = TextBox6.Value
    Cells(ActiveCell.Row + 1, "V").Value = DateAdd("d", Val(TextBox4.Value) * 7, TextBox6.Value)
    
    If CheckBox1 = True Then
        Cells(ActiveCell.Row + 1, "U").FormulaR1C1 = "=RC[-4]+365"
    End If
    

    Range(Cells(ActiveCell.Row, 1), Cells(ActiveCell.Row, 29)).Copy
    Sheets("Archives").Cells(Rows.Count, "A").End(xlUp).Offset(1, 0).PasteSpecial xlPasteValues
        

    Application.EnableEvents = False
    Range(Cells(ActiveCell.Row, 1), Cells(ActiveCell.Row, 29)).ClearContents


    Unload Me
    Application.EnableEvents = True
    Application.ScreenUpdating = True

End Sub

Now I have multiple project number in my Column A Row ("A5:A"): Example P123456, P123456, P123456, E123, E321 (Example only)

Each on a different row. But all matching numbers will all have the same number in Column "M" (Example 001)

My code tells the New row to add +1 to the number in column "M" so the 001 will become 002 but my problem is All P123456 (Let say this was the project triggered in my userform) to change all numbers 001 to 002.

Is this possible? If so how?

If I load in my workbook people will get lost with my instruction...But I could.

Is there a way to imbed a code to change the numbers in my Column "M" Vs my project number to the new updated one?

Thank you,

Excel Noub