It would probably help if this was more in context? Who is Calen or David? Some of us (like me) haven't a clue as to who you are referring to; "Calen" could be a misspelling of Kylen as in Mark Kylen & Ginger. . . David could be Copperfield or Blaine or any number of other Davids that are out there.
Sorry I was assuming since Calen is a artist here people would know his name. And David is the most popular magician in the world so I also assumed you would know his name too. But it is Calen Morelli and David Copperfield that I am talking about.
I'd warn him to get a team of very good lawyers if that's the case, David and were friends for a good while until i mixed business with that friendship. I'll not go into details just tell this chap to protect himself and whatever he creates. . . He should ask Kevin James what such scenarios can wrought.
Craig, I believe that is why Blake and Calen were hired by Chris Kenner. To be on the creative team. As far as I have heard, that is why Dan Harlan was hired back in the 80's or 90's. Rumor has it that he snorted all of his money though. That could be hearsay or the truth...not sure.