Edit quantity

Example response

{
  "campaign": {
    "campaign_checkout_upsell": {
      "items": [
        {
          "date_created": "2023-04-01 00:00:00",
          "date_modified": "2023-04-01 00:00:00"
        }
      ]
    }
  },
  "order": {
    "date_authorized": "2023-04-01 00:00:00",
    "date_ordered": "2023-04-01 00:00:00"
  },
  "offers": [
    {
      "gift_date": "2023-04-01 00:00:00",
      "upsells": [
        {
          "items": [
            {
              "date_created": "2023-04-01 00:00:00",
              "date_modified": "2023-04-01 00:00:00"
            }
          ]
        }
      ]
    }
  ]
}