# Add Runtime Children

Templates describe predictable structure. Resource builders can add child resources when an experiment discovers structure at runtime.


# Add a child resource

Use template name and version:

``` python
with namespace.build_resource(resource_id=collection.id) as builder:
    builder.add_child(
        name="Puck01",
        template_name="Puck",
        template_version="1.0",
    )
```

Child resources are persisted as part of the root aggregate and remain available through the root's `children` dictionary.

Process templates define their ordered steps. Process-run builders record assignments and parameter values for those declared steps; they do not support adding child process steps at runtime.