This is her brief article from thepeerage.com: "Charlotte Frances Bentinck F, #23431, d. 1850 Last Edited May 2009
Charlotte Frances Bentinck married Sir Robert Shore Milnes, 1st Bt., son of John Milnes, on 12 November 1785. She died in 1850.
She was the daughter of Captain John Albert Bentinck and Renira van Tuyll van Serooskerken. Her married name became Milnes."
Her birth date is not listed and is, presumably, unknown.