The Roberts mystery

The problems of researching the family you don't know anything about. I'll bet that it's like a professional genealogist researching a family for someone. There's very little evidence or word-of-mouth about the family I'm looking into. The only one I'm sure about is Edith Roberts (1883-1976), and we know that her father is John Roberts based on the marriage record. We know that he was dead by December 1915, because the marriage record indicates it. Now, from other family members, we know that he was a sailor, and the rumor is that her family was from Wales. Of the records available from 1883-1911, the 3 census records available only narrow the results down a little. Looking at the records that have Edith born between 1881-1885, and who have a John Roberts as a father, we get about 10 people who fit the description. My great-aunt says her mother's name was Maria, and if that's the case, then John was anything but a sailor. One job was a leather stretcher for car seat belts. This is a tough nut to crack, and I'm not sure of how to find out what her mother's name is. My other option is to look for John Roberts death record, but how do we find out which John Roberts is the right one when we don't know for sure which one it will be!