Modifying/creating a new layer in a costmap

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Hey! Currently I am trying to implement/modify layered costmaps. So we have a cost map generated by movebase from the /map topic that we are providing. Now say there is some change in the environment and I want to mark some regions as no-go regions.

These no-go regions will be reflected in a new layer of the costmap (that will be created by a node). The coordinates of these regions should ideally be subscribed to the ROS node, and anytime a new set of coordinates are received on this node, the layer that we created previously should be updated. I have tried going through the docs and tutorials on how to create a new layer, but I can't seem to get it to work with my use case.

Would love some pointers on how to implement this? Thank you!