A result of a search on Ancestry confirms the family sailed to Sydney Australia on 12 October 1955. This is the entry for Lavinia:
Name: Mrs L M Kitchener
Gender: Female
Departure Date: 12 Oct 1955
Port of Departure: London, England
Destination Port: Sydney, Australia
Ship Name: Oronsay
Shipping Line: Anderson, Green and Company, Limited

All members of the family are listed together with dates of birth and address in this country:
9 South Undercliff, Rye, Sussex
Mr A G Kitchener 23 November 1914
Mrs L M Kitchener 11 April 1915
Mr F Kitchener 23 September 1942
Master R Kitchener 6 June 1944
Master A Kitchener 12 February 1946
Miss J M Kitchener 24 February 1950

There is every possibility that the children are still alive.

It would appear that in addition to Lavinia being buried at Macquarie Park Cemetery and Crematorium her husband is also:
Name: Allan Geoffrey Kitchener
Event Type: Burial
Event Date: 2011
Event Place: North Ryde, , New South Wales, Australia
Photograph Included: N
Death Date: 13 May 2011
Affiliate Record Identifier: 145357717
Cemetery: Macquarie Park Cemetery and Crematorium

(The different second forename to that quoted in Baptism transcript is noted)

As stated in MPGriffiths posting Lavinia's first marriage was to Reginald James DUNN (transcript on this site) who had a twin Francis John DUNN who was a witness at the wedding:

Child Surname Child Forename Mother's Former Name Year District Office Register Entry
DUNN Francis John GOODWIN 1916 Forest of Dean Monmouth, Coleford (Sub-district 4) 5 460
DUNN Reginald James GOODWIN 1916 Forest of Dean Monmouth, Coleford (Sub-district 4) 5 459

Sadly Reginald lost his life in WW11 just 2 months after his marriage:
https://www.cwgc.org/find-war-dead/casualty/2775880/dunn,-reginald-james/

The marriage states that Lavinia's father was Benjamin White, Collier and her birth registration tells us that her mother's maiden name is Watkins but I have not found a marriage. However there is a marriage 8 April 1912 at Christchurch between George Edward White and Charlotte Watkins. Witnesses were William Henry Watkins and Lavinia White.
This would appear to be the WHITE family at Joyford Lonk in 1901:

Household Number Given Name Surname Relationship Age Birth Year (Derived) Gender Birth City Birth County Birth Country
31 Henry White Head 61 1840 Male West Dean Gloucestershire England
31 Annie White Wife 51 1850 Female West Dean Gloucestershire England
31 Henry White Son West Dean Gloucestershire England
31 George White Son West Dean Gloucestershire England
31 William White Son 7 1894 Male West Dean Gloucestershire England
31 Lavinia White Daughter 13 1888 Female West Dean Gloucestershire England
31 Richard White Son 11 1890 Male West Dean Gloucestershire England
31 Hubert White Son 6 1895 Male West Dean Gloucestershire England
31 Oliver White Son 12 1889 Male West Dean Gloucestershire England

Mike