3 tribes? Good idea
How about this, very far fetching but anyway: in reward challenge the winning tribe gets to vote who from the ghost tribe comes in back to game. If you are in ghost tribe, and ghost tribe wins, you can not vote for yourself. This would make it more likely for Lil to come back because she might be viewed as least of a threat by Morgan and Drake and they would vote for her to come back rather than the physical people. Also the tribes merge and first individual IC takes place.
However this thing plays out, it will be very interesting to see and how the people react.
Another idea, maybe someone wrote this already: in reward challenge the 3 tribes compete against each other, and whoever wins wins whatever they win. But, in immunity challenge (first individual one at that) there is more at stake for ghost tribe members. If any one person of the ghost tribe would manage to win the immunity, he/she would also earn the right to return to game. This would seem more rightful, since he/she would have proven to be worthy of it against all off Morgan and Drake. This would also explain why this person could not be voted out in first merged tribe council. But, this way it would not be 100% sure that a "ghost" would return to game and it would be exciting to watch.