Interesting postings on Mardens. I have some details that may be useful.
William Marden senior b. circa 1780, Sussex. Married to Charlotte Heasman (William was previously married to unknown). Son William Marden b. 1818, Hartfield Sussex. Had a number of children with Charity Parker (domestic servant) between 1847 and 1854. Children Richard, Amos, George, Charlotte Sarah, Moses, John. William and Charity married in 1863.
Some of the children lived around Withyham, Sussex in the late 1800s. Charlotte Sarah, daughter lived at Friar's Gate, at the bottom of "Marden's Hill" leading to Crowborough. The road still exists.
William and Charity's great-grandson lives in the UK.