Hi,
I have done a bit of research for you. First of all sarah Alice is a different Whitmore born in Farnham to Thomas Whitmore and Eliza Vaas. Your Sarah was born in 1860 or late 1859 (christened in Feb 1860). I cannot find a marriage for Sarah and George Curd but from 1881 census to 1901 we have a Sarah Married to George. Their daughter, one of many married Alfred John Potter of Adelaide Road Croydon in 1901 when she was 17. He was 21 and they were both Flower Hawkers. Alfred was born in Brighton and it is likely they met there as in 1891 susan was living at Cumberland Place Brighton.
As for Mary Roffey, I don't know anything apart from being born in 1829 and coming from Lingfield. John Whitmore I can trace back through Thomas and (S)Frusanna Browne, then John and Anne Miller, then Thomas and Mary Peters married in 1771 and possibly back to Thomas and Ann from Horley in the early 1700s.