The suggestions about Margaret and son Alexander's death notices were just a guess (there are other possibilities for those too).
However this combination of names on electoral rolls does help to suggest that they could be correct.
1958 ER
PATERSON Margaret, 20 Glassop St, Caringbah, Home Duties
PATERSON Alexander, 20 Glassop St, Caringbah, Gun Dresser
PATERSON Samuel, 20 Glassop St, Caringbah, Machinist
1963 Same for Margaret and Alexander (Samuel not at that address)
1968 ditto
1980 ditto
regards,
Ros