I'm Lucy, and I'd be happy to answer your questions today.
Any tenant in common has a 100% undivided interest in the whole property, so they are free to lease their portion. However, if the other owners are living in the property, the one who leases it out could get sued by their protective tenant - one owner of real estate cannot force the others to move out. No one has any more right to use and enjoy the property than anyone else, and a property owner cannot be bound by a lease without his consent. At the same time, it IS a tort to interfere with someone else's contract, so an owner who terminated a lease that was entered into in good faith by another owner (rather than going to court to resolve any disputes) could get sued for damages.
When there are multiple parties who own real estate, and they cannot agree on how it should be best used, any one of them can go to court and file a Petition for Partition, meaning that either (a) one owner will be ordered to buy out everyone else's share (if one - and only one - owner has the means and the desire to do this) or the property will be sold and the profits split among the owners according to their percentages of ownership.
I know this is a bit of a confusing situation, so if you have any questions or concerns about what I've written, please reply so that I may address them. If I did not address the specific thing that you wanted to know, it may not have come across clearly to me, so please restate that question. It's important to me that you are 100% satisfied with the service I provide. Thank you.