Nest Column Values Under Main Column

Sorry about that.  Here you are.

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("Zc6xDoQwCAbgd2HW5NQCddWol5tJTGM63wvc4ttL42A5FsIPXwLHAQGJOZQKDayCGFCbrh9anbWEhJCbPzYXRpaRZ9OsjC3jiknaFt2aUNHo6frTFA2LNQuT7IV9ke4XHjeO3plQXTY0ieg26d3TKH559faq8+qTnOq9WnanBsj5Ag==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Main = _t, Sub = _t, #"Sub-Code" = _t]),
    #"Replaced Value" = Table.SelectRows(Source,each [Main]<>[Sub]),
    #"Renamed Columns" = Table.RenameColumns(#"Replaced Value",{{"Main", "Main/Sub"}}),
    #"Grouped Rows" = Table.Group(#"Renamed Columns", {"Main/Sub"}, {{"Level", each 1, Int64.Type}, {"Data", each Table.RenameColumns ( Table.RemoveColumns ( Table.AddColumn ( _, "Level", each 2, Int64.Type), {"Main/Sub"} ), {{"Sub", "Main/Sub"}} ), type table }}),
    Custom1 = Table.AddColumn ( #"Grouped Rows", "NewTable", each   Table.Combine ( { Table.FromRows({Record.FieldValues(Record.SelectFields (_, {"Level", "Main/Sub"}))}, {"Level", "Main/Sub"}), [Data] } ) ),
    #"Removed Other Columns" = Table.SelectColumns(Custom1,{"NewTable"}),
    #"Expanded NewTable" = Table.ExpandTableColumn(#"Removed Other Columns", "NewTable", {"Level", "Main/Sub", "Sub-Code"}, {"Level", "Main/Sub", "Sub-Code"})
in
    #"Expanded NewTable"