diff --git a/src/agora/io/signal.py b/src/agora/io/signal.py
index 6e8ffd0ae1a377fec4c73998070d5a5a0188f45b..158d522dbd19fc656999a6a7df2955f4157868c3 100644
--- a/src/agora/io/signal.py
+++ b/src/agora/io/signal.py
@@ -39,7 +39,7 @@ class Signal(BridgeH5):
         self.candidate_channels = global_parameters.possible_imaging_channels
 
     def __getitem__(self, dsets: t.Union[str, t.Collection]):
-        """Get and potentially pre-process data from h5 file and return as a dataframe."""
+        """Get and potentially pre-process data from h5 file and return as a data frame."""
         if isinstance(dsets, str):
             return self.get(dsets)
         elif isinstance(dsets, list):
@@ -47,7 +47,7 @@ class Signal(BridgeH5):
             # Check we are not comparing tile-indexed and cell-indexed data
             assert sum(is_bgd) == 0 or sum(is_bgd) == len(
                 dsets
-            ), "Tile data and cell data can't be mixed"
+            ), "Tile data and cell data cannot be mixed."
             return [self.get(dset) for dset in dsets]
         else:
             raise Exception(f"Invalid type {type(dsets)} to get datasets")
@@ -66,12 +66,12 @@ class Signal(BridgeH5):
 
     @staticmethod
     def add_name(df, name):
-        """Add name of the Signal as an attribute to its corresponding dataframe."""
+        """Add name of the Signal as an attribute to its data frame."""
         df.name = name
         return df
 
     def cols_in_mins(self, df: pd.DataFrame):
-        """Convert numerical columns in a dataframe to minutes."""
+        """Convert numerical columns in a data frame to minutes."""
         try:
             df.columns = (df.columns * self.tinterval // 60).astype(int)
         except Exception as e:
@@ -251,6 +251,7 @@ class Signal(BridgeH5):
         dataset: str or t.List[str],
         in_minutes: bool = True,
         lineage: bool = False,
+        **kwargs,
     ) -> pd.DataFrame or t.List[pd.DataFrame]:
         """
         Get raw Signal without merging, picking, and lineage information.
diff --git a/src/postprocessor/grouper.py b/src/postprocessor/grouper.py
index d3699c420dfe908594ac65941c1996808633c0a0..0dca70e0e31f56117077cec0d1cf422956a9bb5c 100644
--- a/src/postprocessor/grouper.py
+++ b/src/postprocessor/grouper.py
@@ -288,16 +288,22 @@ def concat_one_signal(
     elif mode == "raw":
         combined = position.get_raw(path, **kwargs)
     elif mode == "daughters":
-        combined = position.get_raw(path, **kwargs)
+        combined = position.get_raw(path, lineage=True, **kwargs)
         combined = combined.loc[
             combined.index.get_level_values("mother_label") > 0
         ]
+    elif mode == "mothers":
+        combined = position.get_raw(path, lineage=True, **kwargs)
+        combined = combined.loc[
+            combined.index.get_level_values("mother_label") == 0
+        ]
+        combined = combined.droplevel("mother_label")
     elif mode == "families":
         combined = position[path]
     else:
         raise Exception(f"concat_one_signal: {mode} not recognised.")
     if combined is not None:
-        # adjust indices
+        # add position and group as indices
         combined["position"] = position_name
         combined["group"] = group
         combined.set_index(["group", "position"], inplace=True, append=True)