Assign identifier to rows using multiple columns

Hello Anonymous 

you can Fill-down the SSN-column, Group by Name and SSN and add a index column. Expand the grouped table afterwards. Here the M-code

let
    Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("i45W8krMS1VwyU9V0lEyhAGlWB0UCSMYQJdA05GfkQeVMIYBdAkFpdhYAA==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type nullable text) meta [Serialized.Text = true]) in type table [Name = _t, SSN = _t]),
    #"Changed Type" = Table.TransformColumnTypes(Source,{{"Name", type text}, {"SSN", Int64.Type}}),
    #"Filled Down" = Table.FillDown(#"Changed Type",{"SSN"}),
    #"Grouped Rows" = Table.Group(#"Filled Down", {"Name", "SSN"}, {{"AllRows", each _, type table [Name=text, SSN=number]}}),
    #"Removed Other Columns" = Table.SelectColumns(#"Grouped Rows",{"AllRows"}),
    #"Added Index" = Table.AddIndexColumn(#"Removed Other Columns", "Index", 1, 1),
    #"Expanded AllRows" = Table.ExpandTableColumn(#"Added Index", "AllRows", {"Name", "SSN"}, {"Name", "SSN"})
in
    #"Expanded AllRows"

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

If this post helps or solves your problem, please mark it as solution (to help other users find useful content and to acknowledge the work of users that helped you)
Kudoes are nice too

Have fun

Jimmy