Welcome to the community!
Depending on how big the file is, you’ll probably have to do it piece by piece.
There used to be edit and insert modes, but they’ve been scrapped since. https://openai.com/index/gpt-3-edit-insert/ (but they likely didn’t do what you’d hope they do anyways)
Of course you can do it with the command prompt: look for the curl commands in the docs https://platform.openai.com/docs/guides/text-generation/chat-completions-api, and let chatgpt translate them to cmd or powershell for you if necessary.