Merge private attributes in Python

I know that private attributes are loosely defined in Python, but I'm trying to figure out what would be the most lean way of implementing a method to merge together private attributes.

Class Event:
  target_time: datetime
  _names: set

I'm thinking of having a static method to merge together two Events.

@staticmethod
def merge(event1: Event, event2: Event) -> Event:
  new_event = Event()
  new_event = event1._names + event2._names
  return new_event

But I'm unsure if this breaks some good design patterns about private attribute since they are private.