How can you prove other people are living in the rental

[Linda Thomas]

Hello,

half of the time we go do a repair the tenants on the lease are not there at the property and someone we dont know is there. When scheduling repairs tenant says i will be at work but can have someone there. I called gas comp bc i have a feeling and they said the gas isnt in either of my tenants name? Is this enough evidence? Prob not right bc they can give some excuse abt deposit required so put im friend name etc?