I think Linda D gave the best answer. But what are you still thinking. In 30 years I have only done one cash for keys.
You are saying pay money to one tenant to move. Giving rent and deposit back to co tenant. Hopefully you are not pay their brothers friends cousin also. This all sounds crazy. You are in a business to collect money. Not look for every excuse to pay it back.
First is the co tenant garnish-able. If so no way he would get of my lease unless he was paying me.
You want to do this and pay him. Why have a lease if you cant stick with it.
If things go south I want as many people as I can get to garnish.
But remember. This has happened to the best. It is how you learn. Just learn as cheap as disposable. And the same problems could have happened even when you properly screened. And hope I was not to hard on you. We all had to learn at one time.
And the one advantage you have is Nurses make good money so you have an excellent chance of collecting.
Tell the co-tenant if he wants any money now, to get it from the other tenant.
Tell them no one gets off the lease unless both agree to terminate the current lease. And then you can sign a MTM lease with whoever stays.
If neither agrees, then per the current lease both will be legally responsible for all future rents. This alone should be enough to get the co tenant to sign off.
The main tenant should do it because she will not want the co tenant to have any rights to the home. And mention it is MTM since you have more risk with one less cosigner.
Make this happen and wait a month. She is a nurse and needs a place to live. So it could still work out if the problem is gone and you want to wait & see for awhile.
Also my lease states tenants pay for glass breakage no matter how it happened. Make sure you send a bill and demand they pay it with next months rent.