Is it permissible to deal with an employee who offers legal consultations outside of his working hours to help individuals reduce real estate registration fees from 8% to 1% in exchange for a percentage of the profits?

There is no objection to seeking the assistance of an employee to study real estate files outside his official working hours, nor is there any objection to agreeing with him on a known percentage of what the office owner receives as his wage, acting on the permissibility of the wage being a percentage and not a fixed amount, as stated in Kashshaf al-Qina': "If he gives yarn to a man to weave it into a garment for a third or a quarter of its price, it is permissible according to his explicit statement."