If I take a feat that gives me a certain origin but I already have a specific racial origin, do they stack or is my racial origin replaced?
Consider this example. Calistar the Eladrin is a fey creature, but he wants to take the Haunting Shade feat.
Your origin changes to shadow if it isn't already, so you are considered a shadow creature for all effects related to creature origin.
Is he a shadow creature, or both shadow and fey?