在Amadeus Flight Post Booking API中，可以使用以下代码示例将常客旅客号码添加到PNR中：

import requests
import json

# 设置API访问凭证
client_id = "your_client_id"
client_secret = "your_client_secret"

# 获取访问令牌
def get_access_token():
    url = "https://test.api.amadeus.com/v1/security/oauth2/token"
    data = {
        "grant_type": "client_credentials",
        "client_id": client_id,
        "client_secret": client_secret
    }
    response = requests.post(url, data=data)
    access_token = response.json()["access_token"]
    return access_token

# 在PNR中添加常客旅客号码
def add_frequent_traveler_number(pnr, frequent_traveler_number):
    url = f"https://test.api.amadeus.com/v2/booking/flight-order/{pnr}/traveler/{traveler_id}"
    headers = {
        "Authorization": f"Bearer {get_access_token()}",
        "Content-Type": "application/json"
    }
    data = {
        "frequentTravelerNumber": frequent_traveler_number
    }
    response = requests.patch(url, headers=headers, data=json.dumps(data))
    if response.status_code == 200:
        print("常客旅客号码已成功添加到PNR中")
    else:
        print("添加常客旅客号码失败")

# 调用添加常客旅客号码函数
pnr = "ABC123"  # 替换为实际的PNR编号
frequent_traveler_number = "123456789"  # 替换为实际的常客旅客号码
add_frequent_traveler_number(pnr, frequent_traveler_number)

请注意，上述代码示例中的client_id和client_secret需要替换为您自己的API访问凭证。另外，该示例仅适用于Amadeus测试环境，如果要在生产环境中使用，请将URL中的test.api.amadeus.com替换为api.amadeus.com。