I got a response to my question about the search for current Alcott family members from someone in my Louisa May Alcott Facebook group. She writes;
… I read here in the Acknowledgments of Invincible Louisa by Cornelia Meigs that here’s some folks you may want to look up: “For material in this biography, thanks are due, personally, for verbal information from Mrs. Alcott Pratt of Concord, Massachusetts, daughter-in-law of Anna Alcott Pratt”; the other names might not be related?– Miss Clare Endicott Sears of Boston (http://www.fruitlands.org/ces), Miss Sarah Niles of Arlington, etc.
. . .The author – Cornelia Meigs – also acknowledges some other authors: Louisa M. Alcott, Her Life, Letters and Journals, edited by Ednah Cheney, The Alcotts As I Knew Them by Clara Gowing, Recollections of Louisa M. Alcott by Maria S. Porter, Bronson Alcott’s Fruitlands by Clara Endicott Sears, A. Bronson Alcott: His Life and Philosophy by F.B. Sanborn and William T. Harris, and Honor to Louisa Alcott by One Who Knew Her by Julian Hawthorne in the N.Y. Times.