def merge_scores(self,df_addition,reference_markers='all',
                                      addition_markers='all',on=['project_name','sample_name','frame_name','cell_index']):
        """
        Combine CellDataFrames that differ by score composition

        Args:
            df_addition (CellDataFrame): The CellDataFrame to merge scores in from
            reference_markers (list): which scored call names to keep in the this object (default: all)
            addition_markers (list): which scored call names to merge in (default: all)
            on (list): the features to merge cells on

        Returns:
            CellDataFrame,CellDataFrame: returns a passing CellDataFrame where merge criteria were met and a fail CellDataFrame where merge criteria were not met.
        """
        if isinstance(reference_markers, str):
            reference_markers = self.scored_names
        elif reference_markers is None: reference_markers = []
        if isinstance(addition_markers, str):
            addition_markers = df_addition.scored_names
        elif addition_markers is None: addition_markers = []

        df_addition = df_addition.copy()
        df_addition['_key'] = 1
        df = self.merge(df_addition[['scored_calls','_key']+on].rename(columns={'scored_calls':'_addition'}),
                            on = on,
                            how = 'left'
                        )

        df['_sub1'] = df['scored_calls'].apply(lambda x:
                dict((k,x[k]) for k in reference_markers)
            )
        df['_sub2'] = df['_addition'].apply(lambda x:
                dict({}) if x!=x else dict((k,x[k]) for k in addition_markers) # handle NaN where we fail to match properly treat as empty
            )
        # combine the two dictionaries
        df['scored_calls'] = df.apply(lambda x:
                {**x['_sub1'],**x['_sub2']}                    
            ,1)
        df = df.drop(columns=['_sub1','_sub2','_addition'])
        df = df.drop(columns='_key').copy(),df[df['_key'].isna()].drop(columns='_key').copy()
        if self.microns_per_pixel: df[0].microns_per_pixel = self.microns_per_pixel
        if self.microns_per_pixel: df[1].microns_per_pixel = self.microns_per_pixel
        return df