What is the ruling of Islamic law on relatives of employees entering a company's private premises without paying the prescribed entrance fees or completing the duration of stay? And does the sin fall upon the relatives, the employee, or security?

It is not permissible to violate the company's terms regarding entry and stay in its facilities, and the security guard is not allowed to exceed what he has been commanded. If he is authorized to make exceptions for whomever he wishes, then there is no blame upon him. Otherwise, he commits a sin by his transgression and betrayal, just as the worker who admitted them sins if they were aware of the company's terms.