How to adapt map with environment change

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Hello,

My robot is equipped with 2d lidar, so I generate environment map with using gmapping.
After that I control my robot with using navigation stack.

In the future, I would like to have my robot running in our office.
One of my concerns is the changing environment.

In our office, we change the layout of desks, chairs, etc. periodically, about once every few months.
I would like to update the map generated by gmapping, but I'm looking for a way to do this automatically.

One way to do this is to regenerate the map from scratch when the layout changes, but I don't want to do this.
For example, I would like to update only specific areas where the layout of things has changed slightly.

As far as I can tell, gmapping doesn't have the ability to subscribe to map topics in the first place, so I don't think it's possible to update a map from the past.

Is there any way to do this?
It is also possible to use other SLAM packages.

Thanks in advance.

PS

Another thing I'm worried about is if I'm using SLAM correctly.
My idea is basically to generate a map in advance using gmapping, etc., and then use that map to localize its own position and drive autonomously to goals.
I was asked my colleague if it is really SLAM, or if it localize its own position but does not do mapping when it runs autonomously.
I think the process of generating a map in advance is exactly SLAM, but I'm not sure if the autonomous driving after that is correct SLAM robot.