diff --git a/mola_kernel/src/interfaces/FrontEndBase.cpp b/mola_kernel/src/interfaces/FrontEndBase.cpp
index 881ce86b..6a1b0676 100644
--- a/mola_kernel/src/interfaces/FrontEndBase.cpp
+++ b/mola_kernel/src/interfaces/FrontEndBase.cpp
@@ -68,9 +68,10 @@ void FrontEndBase::initialize_common(const Yaml& cfg)
     }
     else
     {
-        MRPT_LOG_WARN(
+        MRPT_LOG_WARN_STREAM(
             "No 'raw_data_source' entry found in the YAML definition for a "
-            "FrontEndBase.");
+            "FrontEndBase: YAML contents:\n"
+            << cfg << "\n");
     }
 
     // Optional: attach to the SLAM backend:
diff --git a/mola_launcher/src/MolaLauncherApp.cpp b/mola_launcher/src/MolaLauncherApp.cpp
index 84ed84d0..da5c2dab 100644
--- a/mola_launcher/src/MolaLauncherApp.cpp
+++ b/mola_launcher/src/MolaLauncherApp.cpp
@@ -274,7 +274,20 @@ void MolaLauncherApp::setup(
 
                 // Overwrite configuration block: the external file should
                 // contain a "params:" YAML map, etc.
+                // But keep other map entries apart of "params":
+                mola::Yaml old = mola::Yaml::Map();
+                for (const auto& [k, v] : info.yaml_cfg_block.asMap())
+                {
+                    if (k.as<std::string>() == "params") continue;
+                    old[k.as<std::string>()] = v;
+                }
+
+                // overwrite:
                 info.yaml_cfg_block = mola::load_yaml_file(absPathParamsFile);
+
+                // apend other entries:
+                for (const auto& [k, v] : old.asMap())
+                    info.yaml_cfg_block[k.as<std::string>()] = v;
             }
 
             MRPT_LOG_INFO_STREAM(