Multiple unrelated singles in duplex

[Renee R.]

I inherited tenants when I bought a duplex last Oct. One unit has three unrelated singles who share the rent equally, pay with one check and are all three on the lease. All was well until recently when one decided to move out. He found a replacement and thought that was it. Long story short, I did a background check on the new person and all worked out. A month later, another one of the tenants wants to move out and doesn’t have a replacement. I explained that the lease is a legal contract and they can’t just come and go as they please (which I’ve learned the prior landlord did allow). The lease is up end of Nov and I wonder if I should just get them out so I don’t have to deal with this going forward. But, a) Dec isn’t a great month to find a new tenant, right? b) How do I avoid multiple single roommate situation going forward? The duplex is very large and has 2 to 4 bedrooms depending on how you use the rooms. I can’t say max 2 people per bedroom since that could potentially be 8 people! I’m wondering if limited the parking to two cars would be the best route. Suggestions are welcome.