Hello Alicia Quah Wei Ling,
Thank you for reaching out to Microsoft Support!
According to the documentation, when calling the createForward endpoint, this method does not need to provide the request body (except in MIME format), so the request body provided when we use JSON format will not work.
To work around this, you can call the Update message endpoint to modify the value of the ccRecipients property after creating the draft.
Hope this helps.
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