Editing draw stream is creation. Once you parse the original the only real way to update the original stream is mark invalid and push in the updated stream. I

Editing draw stream is creation. Once you parse the original the only real way to update the original stream is mark invalid and push in the updated stream. If you are only looking to edit xmp/meta/comments then you could possibly use an edit or amend but would still need one of the pdf libraries to post process.