The harassment accusation is likely baseless due to ownership and lease.
It appears you have a grasp on the situation. I agree treading lightly into the eventual legal battle is the best option. I would review the lease agreement. Upon renewal, don't renew or at least stipulate the building site. I would dance around said uncle until you hold more cards and are well versed in the situation and applicable law. Speak with the other owners individually to see where their feelings fall. May be able to buy them out for more ownership.