On Charmed why does Piper name her second son Chris Perry?

piper in fact named her second son chris, but he got the last name "Halliwell" as opposed to "Perry" ~Vanessa says~ In truth, Pipers second son is named Chris because that was Leo's fathers name they say so in sesion 5... Yes, it's true Christopher got his first name from his paternal grandfather, Christopher Wyatt, and I'm not sure but I'm assuming Chris has Perry as his middle name because it follows the P tradition in the Halliwell family.