Well...that is why I said let it develop to know it is a reincarnation or inherited will...maybe getting DF is a way to pass inherited will....just like how Zoro received Kuina or Ryuma sword to carry their will....Joyboy is back doesn't mean that he is "literally" back...anyways let us get more info regarding this....
Luffy is the reincarnation of Joyboy he can hear to zunesha as Momo so DF is not a factor.
There's a short line in saying inherited will and reincarnation.