About assigning object

im facing an issue while saving objects in objects

i have data that looks alike

 {
      
        "channel": "Domain",
        "config": {
            "countryCode": "91",
            "FieldOperationCompletedEvent": {
                "attrs": {
                    "ProductOrderId": "$.event.userTask"
                }
            }
        }
    } 

I’m getting a value from textbox, Participant is the value from Textbox and im using Reactjs Class Component.
and have produced data like "attrs" : {"key":"value"} and here i want to assign it to Textbox value which is "Participant" : {"attrs" : {"key":"value"}} and store it inside config like

{

        "channel": "Domain",
        "config": {
            "countryCode": "91",
            "FieldOperationCompletedEvent": {
                "attrs": {
                    "ProductOrderId": "$.event.userTask"
                }
            }, 
            "Participant" : {
                 "attrs" : {
                      "key":"value"
                }
             }
      }
}