All that can presently (June 2024) be gleaned about Marion Werth from sheet music covers and by Internet searching is that she was presumably an American actress/singer who has been featured on just one work namely My Melancholy Baby (1911) music by Ernie Burnett, words by George A. Norton and published by Theron C. Bennett Co., New York, USA
Her portrait on the left is taken from that same work.
Surfers are welcome to contribute any further information about this performer.