how does a name gain another name? (for example william/bill)?

Answer 1

through out history boys got their fathers first name and instead of being refereed to as little jack or john or Williams the names were changed so that when talking to them you would know which William you were referring to if you say will enough times sooner or later someone will through in a willy then you have to go to bill and this billy it helps to avoid calling someone so and so the third or forth, which is a bit too stuffy for most people

Answer 2

Yeah! Or John gets Jack. Edward gets Ted. How does that happen? Good question.