I usually tell researchers if they spend more than 5 minutes searching for a person in an online database, it's time to get off the computer and organize your search procedure. The first step is to determine if it would be more efficient to search the database manually, especially if certain details about the family are known that would make manual searching easier.
If manual searching isn't going to work, make a chart and organize your searches by how you will be entering the search terms. Think about:
place of birth
date of birth
other search parameters
Chart up how you will perform your searches and do them systematically. You might be surprised at the results.