Whenever a transit district acquires the property and franchises of any company or companies operating a transit service within its district all employees of such company or companies who are necessary for the operation of such district, except executive and administrative officers, shall become employees of such district and shall be credited by the district with all seniority rights, sick leave and vacation, insurance and pension benefits in accordance with the records or labor agreements of the acquired company or companies. Such district shall assume and observe all pension obligations of such acquired company or companies, and members and beneficiaries of any pension or retirement system or other benefits established by the acquired company or companies shall continue to have rights, privileges, benefits, obligations and status with respect to such established systems. Such district shall assume and observe all labor contracts of such company or companies in existence at the time of transfer and all obligations incurred by such contracts in regard to wages, salaries, hours, sick leave, working conditions, collective bargaining, and pension or retirement provisions. Such district, through its board, may enter into agreements with representatives of its employees relative to the transfer or establishment of pension trust funds to or under the joint control of such district and representatives of its employees, and shall have all powers necessary to maintain and administer such trust funds jointly with representatives of its employees. No employee of any such acquired company who is transferred to a position with a district shall, by reason of such transfer, be placed in any worse position with respect to workers’ compensation, pension, seniority, wages, sick leave, vacation, health and welfare insurance or any other benefit than he enjoyed as an employee of such company.