How to dynamically create or modify terrain

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I run Gazebo with another 'partner' simulation, that provides terrain info to Gazebo around the actor at runtime, via C++ plugin.

So I want to put a small patch of terrain under the actor, say 10x10 vertex grid, and have a plugin that will dynamically change the grid points altitude.

How can I modify vertex grid at runtime in Gazebo from a C++ Plugin? If that is not possible, can I at least create/destroy collider geometry at runtime in Gazebo?