{
  keys: [
    {
       rowid: "P2"
    }
  ]
}

{
  keys: [
    {
      rowid: "P2"
    }
  ]
  overrides: {
    Party: {
      rowidObject: "P1",
      firstName: "Serge",   //override the value for the first name
      Telephone: {   // override which Telephone child records to merge
        item:[
          {
            rowidObject: "T1",
            MERGE: {
              item: [   // to remove the original merge candidates, specify null
                null,
                null
              ],
              $original: {
                item: [
                  {key:{rowid: "T2"}},
                  {key:{rowid: "T3"}}
                ]
              }
            }
          },
          {
            rowidObject: "T4",
            MERGE: {
              item: [   // to add or change merge candidates, specify matched records
                {key:{rowid: "T2"}}
              ],
            $original: {
              item: [
                null
              ]
            }
          }
        ]
      }
    }
  }
}