How can I cover new information from localmap onto globalmap (refresh global map while navigation)?

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I've got a global map as static_map topic for rviz.

But the real environment, our office, often changes, such as the positions of chairs and desks.

Though the environment does change, yet it's basically the same.

So I want to renew the map of some certain subarea without a thorough rescanning around the entire office.

How can I cover new information from local map onto global map?

May I set a trigger, like"Z" button on the keyboard, in a launch file to actively update the map?