PQ - Concatenation by condition (XL2016)

Source				Result
#	Owner	Make		Owner	Car
1	Jeremy	Ford		Jeremy	Ford
2	Jill	Toyota		Jill	Toyota
3	Jack	Toyota		Jack	Toyota
4	Arnold	Ford		Arnold	Ford,Holden,Mazda,Mercedes
5	Arnold	Holden		Sage	Toyota
6	Arnold	Mazda		Patrick	Toyota,Tesla
7	Arnold	Mercedes		Alex	Unknown
8	Sage	Toyota		Rain	Tesla
9	Patrick	Toyota
10	Patrick	Tesla
11	Alex	Unknown
12	Rain	Tesla

Output must retain hierarchy that input has i.e. Jeremy must remain on top, Jill must remain the next, etc.

Code:

---

// Table1
let
    Source = Excel.CurrentWorkbook(){[Name="Table1"]}[Content],
    Grp = Table.Group(Source, {"Owner"}, {{"All", each _, type table [#"#"=number, Owner=text, Make=text]}}),
    List = Table.AddColumn(Grp, "Car", each [All][Make]),
    Ext = Table.TransformColumns(List, {"Car", each Text.Combine(List.Transform(_, Text.From), ","), type text})
in
    Ext

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