I think you might have some of your research a bit tangled. Louisa Edyvean was NOT the illegitimate daughter of Mellisent. In fact Mellisent was married to Robert EDYVEAN - Louisa is his daughter. Robert died in 1828 and Louisa was bought up by her grandmother (Elizabeth Symons Edyvean) and aunty Loveday Edyvean following the death of her mother Melicent in abt 1829. She appears in the 1841 census with them. Robert EDYVEAN is my 4g uncle