Fill rows based on combined values from succeeding rows

Hi Anonymous 

Does every customer have the same 4 rows? Here is one way, otherwise you need other approaches 

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("Xcw7DoAgEADRq5itafQK9DaWhILPAhZIgkvB7RVJiNq+SUYI4OWkFDFPq4o4AwOlFEgmYKOMSIO11g/znepAY0zHVA7KtZG1ttP7u9wBEf/fxs6577eh9/79bRRCACkv", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Column1 = _t, Column2 = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Column1", type text}, {"Column2", type text}}),
    #"Added Index" = Table.AddIndexColumn(#"Changed Type", "Index", 0, 1, Int64.Type),
    #"Added Custom" = Table.AddColumn(#"Added Index", "Custom", each Number.RoundTowardZero([Index]/4)),
    #"Grouped Rows" = Table.Group(#"Added Custom", {"Custom"}, {{"all", each Text.Combine( _[Column1],",") }}),
    #"Merged Queries" = Table.NestedJoin(#"Added Custom", {"Custom"}, #"Grouped Rows", {"Custom"}, "Grouped Rows", JoinKind.LeftOuter),
    #"Expanded Grouped Rows" = Table.ExpandTableColumn(#"Merged Queries", "Grouped Rows", {"all"}, {"all"}),
    #"Removed Other Columns" = Table.SelectColumns(#"Expanded Grouped Rows",{"all", "Column2"})
in
    #"Removed Other Columns"