Outgoing tenants family

[Ron Tafoya]

hi all.  

I have an outgoing tenant which her 30 days notice ends this week on 8-19-2016.   Tenant is already moved out  but legally has property until 30day notice expires.   

Outgoing tenant has a sister that shows up randomly and goes into backyard for unknown reasons. She is not on lease.  

Can I pad-lock the gate keeping her out of backyard legally?

its unknown what she is doing or if tenant asked her to "check" to make sure it's still unoccupied.   

What are you thoughts on this

Thank you once again!

Ron