Multi-Select Lookup

Multi-Select Lookup

I'm using python sdk 3.x.x
I can't find documentation on how to update Multi-Select Lookup in a record
  1. ro = RecordOperations()
    request = BodyWrapper()
    record_list = []
    record = Record()
    record.set_id(record_id)
    record.add_key_value(record_field, '??')
    record_list.append(record)
    request.set_data(record_list)

    response = ro.update_records(module_name, request)
Do I need to add a relationship between two entities, do I have to set it by populating the Multi-Select Lookup from one of the two or do I have to populate the relationship entity?