Hello Jean,
I don't know how you would go about locating the ELLIOTTs as there is not really any online data after 1954.
Francis Thomas, Norman Edwin Harold and Keith Douglas ELLIOTT were all still in the ACT in 1954.
Perhaps it might be best if you could somehow connect with a perosn who was in the ACT mid 1950s who may have known the family etc. I was lucky in researching my grandmother's family, a lady I knew was born and grew up in the area, when she went back for a holiday asked about my clan and managed to put me in touch with two of my great uncles.
Phyllis Margaret ELLIOTT (shown below) appears to have been the wife of Francis Thomas, maybe there was some family information in one of the notices -
www.ryersonindex.orgSorry, I can not be of any help to you; good luck!!
SOURCE:
www.ryersonindex.orgSurname Given Names Notice Type Date Type Age Other Details Publication Published
ELLIOTT Phyllis Margaret Death notice 30MAY2004 Death 77 at Queanbeyan Nusing Home Canberra Times 31MAY2004
ELLIOTT Phyllis Margaret Funeral notice 03JUN2004 Funeral at Queanbeyan Canberra Times 01JUN2004