Proof of Residency/Additional Occupant

[Mark Smith]

We're pretty certain my first floor tenant has taken an additional occupant since signing her lease (about 4-5 months after the lease began). The lease states there would be three occupants, and this would be he fourth. It also states that there is an exception for visitors up to 14 days, which would mean anything longer than 14 days would be considered an occupant. This would mean a 25% rent increase. Is there a way for me to prove that he is living there? We have been working on the upstairs apartment and he is there in the morning when we get there and at night when we leave.