Who is [Sarah] Sally Franklin from Benjamin Franklin: An American Life and what is their importance?

Sally Franklin was Franklin's only legitimate child. She is described as bright, loyal, and an excellent hostess. She traveled to Boston with him once but, like Deborah, ultimately preferred the comforts of home. Sally married Richard Bache, a struggling merchant, in 1767 without her father's permission. He later approved of the match and doted on his grandson, Benny.