At the Watertown, MA public library, there is a book "A NEW ENGLAND FAMILY AND THEIR FRENCH CONNECTIONS"This book was privately published in 1930. (the book starts out with the Fowle and Cooke families - Susanna's parents)
There is a chapter on the HUNNEWELL FAMILY of Dr. Walter Hunnewell of Watertown, MA and Susanna Cooke his wife.There is a photo of a youth Hollis and his father, a photo of the country house of Hollis and a later photo of Hollis.There is a chapter of this book devoted to this family.
The book states that Walter is the son of Richard Hunnewell of Cambridge and Eunice Thompson of Cambridge.
Richard is said to be the 4th son of Charles Hunnewell
Charles is listed as the s. of Charles Hunnewell & Elizabeth Davis
Charles is listed as the son of Ambrose Hunniwell who moved from Maine to Charlestown
there is also some information going back to England.