Not related at all.
Hannah's Daphne, is below.
Birth of Daphne SLACK in 1911:
4897/1911 SLACK DAPHNE L STEPHEN HANNAH J INVERELL
Marriage at Inverell in 1932:
3874/1932 MUNSIE ALLAN C SLACK DAPHNE L A INVERELL
Death of a daughter, at Inverell, in 1950:
29623/1950 MUNSIE JANELLE ALMA LEA ALLAN COVENTRY DAPHNE LORNA A INVERELL
Her husbands WW2 record:
Name: MUNSIE, ALLAN COVENTRY
Service: Royal Australian Air Force
Service Number: 62875
Date of Birth: 30 Sep 1906
Place of Birth: GUYRA, NSW
Date of Enlistment: 16 Mar 1942
Locality on Enlistment: ASHFORD, NSW
Place of Enlistment: SYDNEY, NSW
Next of Kin: MUNSIE, DAPHNE
Date of Discharge: 22 Jan 1946
Rank: Leading Aircraftman
Posting at Discharge: 3 Mobile Works Squadron
WW2 Honours and Gallantry: None for display
Prisoner of War: No
Then her husbands death in 1976:
100544/1976 MUNSIE ALLAN COVENTRY WILLIAM REDMOND CLARA
This is a different Daphne SLACK, to the one in Rob's family.
Here is the birth of Rob's, Daphne:
4899/1911 SLACK IRENE E JOSEPH S IVY E INVERELL
Just two BDM numbers after the other Daphne!