Hello Doug, I am not a real estate attorney nor is this legal advice.Unless someone's state has specific laws banning contract assignments you should be fine doing the following.  

.: Quote from @Dustin Tucker: Hello Joelle, What are the laws like for landlords, how long does it take for an eviction to take place?

An attorney that only does litigation or maritime law, not so good.

There are thousands of pages on consumer protection laws and regulations that depending how you go about doing a subject to could be against these laws and regulations. so like most things - is itillegal - it depends.  

Tenant covenants and agrees to pay interest at the maximum lawful rate or eighteen percent (18%) interest, whichever is less, compounded annually, on all unpaid Rent, damages, and other amounts owed by Tenant, excluding late fees, from that date of Landlord’s final accounting until such time Tenant pays all such outstanding amounts.

Lenders will want to see the filed Articles of Organization, an Operating Agreement that you can get from your attorney or, if you're brave and it's just you on the LLC, some people use Legal Zoom or Law Depot.

If not, you’ll need to resolve these liens, which could complicate the investment.Current Occupants: The family living in the property could be protected under Massachusetts’ tenant and housing laws.

Regulations & Compliance: What's the best way to research local STR laws and avoid potential regulatory issues?

In the meantime I would love to have some helpful information or ideas to share with the buyers when we meet and ideally an agreement/contract we could fill out together once new terms are agreed to and then share that with the attorney so he could draft up the formal instrument for recording.If you have experience with this type of scenario, I’d love to hear any recommendations you have or any helpful resources you could point me to for the appropriate paperwork.Under foreclosure laws, you have to send appropriate notices and try to work with the borrower and offer a loan mod before foreclosure anyway. 

Rent control laws are market specific.