While thinking of a decent Japanese proverb, I think the number one step is to ascertain the date of birth of William, Nicholas and Edward. After that [as I'm writing about this - census records come to mind, although I have no idea how to go about that] and then go from there.
Going back to the source you've linked - done a brief skim read - going to try to find the time to have a deeper more in-depth analysis at a later date