In a case in which there are collective agreements, often those collective agreements will set out a process by which they would deal with harassment and violence in the workplace. Those collective agreements will need to abide by the legislation, so in some cases that may mean the processes will need to be adjusted in order to be consistent with the legislation.
If there is a process in place, though, through a collective agreement, as long as it adheres to the requirements of the legislation, that's fine.