Tenant moving out 1 month early, father of her child (other tenant) in jail.

[Jonathan Komarmy]

I'm new to this and have 2 units, a 4 plex and a duplex.  All my tenants came with the purchases.  This one had the father of her 3 month child picked up by INS and he is jail.  They are not married, but both on the lease.  He had a trial on the 17th and was not released.  She is moving in with her mother and wants out of the lease early.  I'm fine with this, and during their stay they always paid on time and kept things in order.  I'm curious if I write up an agreement and she is the only signer if I am opening myself up for trouble.

Edit - I hit enter trying to add the location and it posted.  The property is in Lansing, MI.  I was thinking of writing the security deposit check to both of them so he has to sign for it to get cashed.  Thanks for any advice!