Ending lease early. What forms do I need?

[Bryan Petrinec]

A tenant has indicated she wants out of her lease early due to her mother's failing health.  Regardless of the reason, I am glad to let her out early as she was an inherited tenant and she has been a concern since day one.  So far, rent has been paid, but I have had several requests for delayed rent payments and when I remind her of the late fees, she seems to find the funds. 

However, I am holding her to her lease obligations while I look for another tenant.  Given that her lease expires at the end of July '18, I want to get something signed stating that she will move if another tenant is qualified and moves in prior to the end of her lease.  I don't want her changing her mind at the last minute causing me to turn away a qualified new tenant.  

Is there a stock form for this sort of thing?  Or can someone share key points that would go into this document?

Ultimately, I don't think she has the income to support the rent and this will be a win-win if she can get out a few months early. I just want to get something in writing that commits her to this process and she will vacate at the appropriate time.

Let me know what you would do.  Thanks!