I think there is something wrong chronologically somewhere.
Even if Rebecca Chapman was only 14 or 15 when she married her first husband in 1637, then she is still going to be in her late forties when she marries her third husband in 1669, which makes it unlikely she would have had a daughter with him. Unless my maths is out?
Maybe both men named Richard Lucy married women with first name Rebecca and they have become confused? Maybe Rebecca isn't the mother of Rowland Lytton's daughter?