How to launch a node with it's dependencies have started

edit

I have 5 launch file. Some node must start when some nodes have started , or they cannot work.

If all the nodes are written by myself, it is easy to deal with.

But now, I use some packages like moveit, whose code is not in my workspace and I donnot want to rewrite it :

<node name="move_group" launch-prefix="$(arg launch_prefix)" pkg="moveit_ros_move_group" type="move_group" respawn="false" output="screen" args="$(arg command_args)">

https://github.com/ros/ros_comm/issue...