Weird Owner & Tenant Issue

[Chris G.]

I manage a large house that sits on around 25 acres of land with a private lake. On the other side of the lake there is a small cottage. Before renting the owner mentioned he'd be coming and using that cottage when he fixes issues on the large home which would be around everything 3-4 months. In the tenants lease it states that the small cottage does not come with the rent. I verbally mentioned this to the tenants when moving in too, since the owner would prefer to do all the small repairs and maintenance to save money. However today the owners sister didn't give me a 24 hour notice but instead gave me a 2-3 hour notice that she was going to the property to look at the small cottage. The tenants texted me complaining that they didn't feel comfortable with the owner/sister there even though it's a different house. They also stated the owner would be staying the night and would use utilities which the the tenants pay for. Not sure if anyone has any insight to this as far as if this is right or legality goes. The owners are from a different country so I don't think they think anything is wrong or weird about this but the tenants do.