Promote headers before expanding tables

Table.TransformColumns(Source, {{"Data", each Table.PromoteHeaders(_), type table}})

let
  Conditions = {
    [ColumnName] = "1501", 
    [ColumnName] = "1500", 
    [ColumnName] >= "1100" and [ColumnName] < "1200"
  }, 
  Results = {"FFPC", "PCFam", "Différentielle"}
in
  Results{List.PositionOf(Conditions, true)}