I am a great-great-great granddaughter of Preston Chaffee and Nancy Hewitt. They had eight children, including Milo Joseph, but I don't know of a Louisa among them, or a Numa Arnold. Milo was born in 1846 as well, so I am wondering if perhaps Louisa was a sister of Nancy. On an 1887 map of Center Creek, I do see a lot belonging to a J. Arnold in section 12, so you could have a relation there. I am sorry that I cannot be more helpful.