3 tenants sign lease, 1 moves out, new 1 moves in-new lease?

[Scott Ficek]

I am interested in hearing other landlords thoughts on this. I don't see it often, but just had it happen to me and got me thinking maybe I am putting myself in a bad situation.

Three roommates move in and sign the lease on July 1. September 1, two of the three call and say they kicked the 3rd one out (and they say she agreed to move out). They found a new roommate and want to put him on the lease. They can't find 1st tenant now as she has disappeared with boyfriend.

Give me your thoughts on how to minimize my exposure. Do you sign a new lease noting that it cancels the first lease? Do you stay out of it and have them sign a sublease with the new roommate?