does this work for you?

[
  {
    "operation": "modify-default-beta",
    "spec": {
      "Booking": {
        "*": {
          "*": "Booking[&1].&",
          "BookingLines": {
            "BookingLine": {
              "*": {
                "Metadata": {
                  "TrackingList": {
                    "Tracking": "null"
                  }
                }
              }
            }
          }
        }
      }
    }
  },
  {
    "operation": "shift",
    "spec": {
      "Booking": {
        "*": {
          "BookingLines": {
            "BookingLine": "Booking[&2].BookingLines.BookingLine"
          },
          "*": "&2[&1].&"
        }
      }
    }
  }
 ,
  {
    "operation": "shift",
    "spec": {
      "Booking": {
        "*": {
          "*": "Booking[&1].&",
          "BookingType": {
            "@": "Booking[&2].&1",
            "3": {
              "@(2,BookingLines)": {
                "BookingLine": {
                  "*": {
                    "Metadata": {
                      "TrackingList": {
                        "Tracking": {
                          "null": {
                            "#N": "Booking[&10].BookingLines.BookingLine[&5].Metadata.TrackingAvailable"
                          },
                          "*": {
                            "#Y": "Booking[&10].BookingLines.BookingLine[&5].Metadata.TrackingAvailable"
                          }
                        }
                      }
                    }
                  }
                }
              }
            }
          }
        }
      }
    }
  }
]