What documents do we need to take our granddaughter out of Thailand for a holiday with her father?

To take your granddaughter out of Thailand for a holiday with her father, you will need a consent letter signed by her mother, who is Thai. It is also advisable to bring a copy of her birth certificate. Additionally, having a letter that authorizes you to make medical decisions in case of an emergency could be important. You may need to check with your local Amphur (district office) regarding any required official signatures or additional documentation.