Adding custom rows in Power Query

Hello peterso 

you can apply Table.Group twice to your orignal data and then combine your source with the results of your Table.Groups

Here the code to understand it better

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45WMlTSUUrMq1QoSa0oATJNodjCQClWB0MWxDUD0UYQaSNUaWMgNgfTWCTBpoJooNZYAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Assignment = _t, Scopes = _t, Labor = _t, Materials = _t, Rent = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Assignment", Int64.Type}, {"Scopes", type text}, {"Labor", Int64.Type}, {"Materials", Int64.Type}, {"Rent", Int64.Type}}),
    CreateCustomTextRow = Table.Group(#"Changed Type", {"Assignment"}, {{"Rent", each List.Sum([Rent]), type number}, {"Scopes", each Text.From([Assignment]{0})&".CustomText"}}),
    CreateAnotherCustomTextRow = Table.Group(#"Changed Type", {"Assignment"}, {{"Rent", each 0, type number}, {"Scopes", each Text.From([Assignment]{0})&".AnotherCustomText"}}),
    Combine = Table.Combine({#"Changed Type", CreateCustomTextRow, CreateAnotherCustomTextRow})
in
    Combine

Copy paste this code to the advanced editor in a new blank query to see how the solution works.

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Kudoes are nice too

Have fun

Jimmy