add example where all fathers in a line have no marked mutations

pyrat-data-single-mutation.csv

@@ -19,3 +19,5 @@ ID-017,Line-B,12/12/2025,ID-F10,ID-M11,End of experiment,Mut-B,wt,,,,,Mut-B,wt,,
 ID-018,Line-B,18/12/2025,ID-F11,ID-M12,End of experiment,Mut-B,het,,,,,Mut-B,wt,,,,,Mut-B,hom,,,,
 ID-019,Line-B,01/12/2025,ID-F11,ID-M12,End of experiment,Mut-B,het,,,,,Mut-B,wt,,,,,Mut-B,hom,,,,
 ID-020,Line-B,01/12/2025,ID-F11,ID-M12,End of experiment,Mut-B,het,,,,,Mut-B,wt,,,,,Mut-B,hom,,,,
+ID-021,Line-C,01/12/2025,ID-F11,ID-M12,End of experiment,Mut-C,het,,,,,,,,,,,Mut-C,hom,,,,
+ID-022,Line-C,01/12/2025,ID-F11,ID-M12,End of experiment,Mut-C,het,,,,,,,,,,,Mut-C,hom,,,,

standardised-data-single-mutation.csv

@@ -19,3 +19,5 @@ ID-017,Line-B,12/12/2025,ID-F10,ID-M11,End of experiment,1,Mut-B,wt,wt,het
 ID-018,Line-B,18/12/2025,ID-F11,ID-M12,End of experiment,1,Mut-B,het,wt,hom
 ID-019,Line-B,01/12/2025,ID-F11,ID-M12,End of experiment,1,Mut-B,het,wt,hom
 ID-020,Line-B,01/12/2025,ID-F11,ID-M12,End of experiment,1,Mut-B,het,wt,hom
+ID-021,Line-C,01/12/2025,ID-F11,ID-M12,End of experiment,1,Mut-B,het,wt,hom
+ID-022,Line-C,01/12/2025,ID-F11,ID-M12,End of experiment,1,Mut-B,het,wt,hom