Apply external force to a surface, not to a point

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Hi, I want to apply some force to a surface or multiple points on Gazebo. I used rosservice /gazebo/apply_body_wrench to apply external force to a point so I tried to call rosservice two time at a time by using &&. For example, rosservice call /gazebo/apply_body_wrench ~~~~~ && rosservice call /gazebo/apply_body_wrench. When I called the rosservices at a time, there was some delay between two rosservice.

Is there any way I can apply external force to a surface or multiple points at a same time?

I appreciate it.