diff --git a/bin/generate.py b/bin/generate.py
index 18f3bcb3..f695add0 100644
--- a/bin/generate.py
+++ b/bin/generate.py
@@ -519,6 +519,9 @@ def __init__(self, problem, generator_config, key, name: str, yaml, parent):
                 if ext in self.hardcoded:
                     hashes[ext] = hash_string(self.hardcoded[ext])
 
+        if isinstance(yaml, ruamel.yaml.comments.CommentedMap):
+            print(yaml.__dict__)
+
         # Warn/Error for unknown keys.
         for key in yaml:
             if key in RESERVED_TESTCASE_KEYS:
@@ -1626,9 +1629,11 @@ def get_or_add(yaml, key, t=ruamel.yaml.comments.CommentedMap):
                 entry.append(ruamel.yaml.comments.CommentedMap())
                 path_in_gen = in_file.relative_to('generators')
                 name = path_in_gen.as_posix().replace('/', '_')
-                entry[-1][f'{name}_{in_file.stem}'] = {
-                    'copy': path_in_gen.with_suffix('').as_posix()
-                }
+                new = ruamel.yaml.comments.CommentedMap(
+                    {'copy': path_in_gen.with_suffix('').as_posix()}
+                )
+                new.fa.set_flow_style()
+                entry[-1][f'{name}_{in_file.stem}'] = new
                 bar.log('added to generators.yaml.')
             bar.done()
 
diff --git a/doc/commands.md b/doc/commands.md
index 9e9a273a..6a8f1d02 100644
--- a/doc/commands.md
+++ b/doc/commands.md
@@ -14,7 +14,7 @@ This lists all subcommands and their most important options.
 - Problem development:
   - [`bt run [-v] [-t TIMELIMIT] [submissions [submissions ...]] [testcases [testcases ...]]`](#run)
   - [`bt test [-v] [-t TIMEOUT] submission [--interactive | --samples | [testcases [testcases ...]]]`](#test)
-  - [`bt generate [-v] [-t TIMEOUT] [--clean] [--check-deterministic] [--jobs JOBS] [--no-validators] [--no-visualizer] [testcases [testcases ...]]`](#generate)
+  - [`bt generate [-v] [-t TIMEOUT] [--add] [--clean] [--check-deterministic] [--jobs JOBS] [--no-validators] [--no-visualizer] [testcases [testcases ...]]`](#generate)
   - [`bt pdf [-v] [--all] [--web] [--cp] [--no-timelimit] [--language LANG]`](#pdf)
   - [`bt solutions [-v] [--web] [--cp] [--order ORDER]`](#solutions)
   - [`bt stats`](#stats)
@@ -156,6 +156,7 @@ Pass a list of testcases or directories to only generate a subset of data. See [
 **Flags**
 
 - `--check-deterministic`: Check that the .in files are generated deterministically for all test cases, skipping the up-to-date check.
+- `--add [<testcases>, <directories>]`: Add the testcases (inside the directories) as `copy` entries in the `generator.yaml`
 - `--clean`: Delete all cached files.
 - `--jobs <number>`/`-j <number>`: The number of parallel jobs to use when generating testcases. Defaults to half the number of cores. Set to `0` to disable parallelization.
 - `--timeout <seconds>`/`-t <seconds>`: Override the default timeout for generators and visualizers (`30s`) and submissions (`1.5*timelimit+1`).