I want to do replacement or addition to json in python?

Question

Python

Here I have a json file:

{
  "894452684072046652": [
    {
      "welcome": {
        "text": "Ты должен(на) указать текст прощание."
      }
    }
  ]
},
{
  "89445266072046658": [
    {
      "welcome": {
        "text": "Ты должен(на) указать текст прощание."
      }
    }
  ]
}

I want if 894452684072046652 this id is not in the file then add it and if not then replace the text field