Change values in json item which is list

I need to change values of items "Id" "SummaryId" and "CoworkersId" in my json. I have already code which will change values of "Id" and "SummaryId". Code below generates new unique Id for these 2 items. I need that this code will change "CoworkersId" as well. As you can see the same value is in these 3 items – a4555752s. The issue is that item "CoworkersId" is a list, not a string and contain 2 elements.

import json
import random

class Cache:
    # A dictionary that keeps a record of "seen" keys
    key_cache = {}

    @classmethod
    def generate_replacement_key(cls, key: str) -> str:
        """
            If key has already been seen, then return the cached key for that, 
            otherwise generate and store a new key.
        """
        new_key = cls.key_cache.setdefault(key, cls.generate_random_key())
        return new_key
    
    @classmethod
    def generate_random_key(cls) -> str:
        """
            returns a random key, that hasn't been generated before
        """
        new_key = str(random.randint(1000, 1000000))
        if new_key in cls.key_cache.values():
            return cls.generate_random_key()
        return new_key
        
a = '''
{
    "people": [
        {
            "Name": "Jan",
            "Lastname": "Szewc",
            "Id": "a4555752s"
        },
        {
            "Name": "Marek",
            "Lastname": "Piorun",
            "Id": "a4asa85",
            "SummaryId": "a4555752s"
        },
        {
            "Name": "Mikolaj",
            "Lastname": "Ciekasz",
            "Id": "a4ddd244",
            "ManagerId": "a4555752s",
            "CoworkersId":
            [   "1278978",
                "a4555752s"]
        }
]}
'''
data = json.loads(a)


for people in data["people"]:
    # use walrus operator to make less boilerplate-code.
    if (id_string := people.get("Id")): # use dict.get to avoid key-errors.
        people["Id"] = Cache.generate_replacement_key(id_string)
    if (summary_id_string := people.get("SummaryId")):
        people["SummaryId"] = Cache.generate_replacement_key(summary_id_string)
print(json.dumps(data, indent=2))

I need that values of all 3 elements "Id", "SummaryId" and "CoworkersId" will be changed.