Create version by adding new files to the dataset without deleting all the existing files in that version.

I'm using the Python API, often I need to update the dataset with a new file along with the old ones, but when I do `api.dataset_create_version("./folder", version_notes=f"Updated on {date}")` it just creates a new version with just the files under the folder. I need the new files to exist along with the old files, how do I achieve it?