I agree it would be cool to be able to make other characters (both our own and possibly our friends) I have no idea how hard it would be to accomplish, but it would be nice.
I agree on that, that sound as a very nice feature. Although then there exists a problem with which role the said crewmember would have, and what happens when your friends joins the game.
Yeah, I don't really have an answer for the role thing, and the best I've got for the 'friend comes back online thing' is a message saying they've had to return to their own adventures or some such. Though I can see that leading to... awkward situations.
