Tenant Lease Problem

[Hank Walter]

I have a rental that I homestead and rent to my friend, and a friend and his girlfriend. The friend and girlfriend are looking for some apart and she has informed she will be moving out in 1 - 2 months. 

They were originally given a lease to sign within the first week of moving in. My friend had the lease looked over by their family friend who happen to be a contract lawyer and didn't sign yet. After several weeks, the lawyer finally returned the lease with several comments, mostly clarification about the pet policy. (The cats are poorly behaved and leave behind a mess around the liter box area) My friend wanted the clarifications added to protect him as a tenant more clearly I guess, even though it is the generic Minnesota Lease. They still have not signed their lease after adding the pet policy information. My other fear is that she will just try to move in with a friend (Rent Free) but still come over every night and still spend considerable time around the place. 

They have been renting from me since September of 2019 and have neglected to sign the lease after months of notice and sitting on the kitchen table and hung on fridge. The other tenant signed it the day he was given it. 

My questions are... Can I have the girlfriend pay me the remaining lease amount or not because she has evaded signing the lease? Also since the boyfriend never signed either could I still increase his rate? Would a small claims court see them as month-to-month renters? Is the girlfriend still going to be responsible for her cats odor and carpet clawing? Am I just screwed out of my rent because they continue to wait this long to sign? Could I evict them because they never signed the lease? 

Any Help is Appreciated.