Use an individual input for each name in the creator field. Remember that you are thinking about the creator for an individual item in the book rather than the entire book.

Illustrators should be listed for illustrations.

Binders should be listed for all parts of a binding, including pastedowns and endpapers.

Printers should be listed for text.

Authors should be listed for reviews and letters.

The author of the text should not be included (Elizabeth Wetherell / Susan Warner) unless speaking of a letter written by her, or in the case of a TEI document or epub.