Difference between "Trustee" and "Landlord"?

A few months ago my mother in law ped away and left a land in a trust to her eight children (one of them being my husband). We have been living on the property in one of the houses for seven years, paying rent (to his mother), taking care of her physically, and maintaining the half acre property ourselves. It was agreed between the siblings after his mother's death that we would move into the main house and live on property in order to maintain the property as the caretakers (1/2 acre yard, house, etc), but still pay the "rent" to the "trustee" sister. A few months later she arrived unannounced at the front door with a Landlord/Tenant agreement and told my husband that if he did not sign it she was going to kick him out. Her "rent" was paid on time, and property looks like a park. Can she demand this since they both are equal owners in the trust? I am confused! Thank you!