I am composing a robot that consists of several independent parts (for example, a robot hand mounted on an arm).

So far, my "assembly" procedure has been a mix of two approaches:

1. Create a single xacro file that includes other xacro files (for each robot), and define a link between them. This results in a single /robot_description parameter
2. Load two robots into their own namespaces (e.g., arm/robot_description and hand/robot_description), then define a transform using static_transform_publisher.

What is considered the best style for doing a complex assemblage of robots? Note that here I'm talking about linking multiple components into a single robot, not multiple independent robots.