You said that you didn't have much information about Sarah Jane SINGLETON. You may already have this, so apologies if I'm telling you what you already know.
The Australian Birth Index has two entries for a Sarah Jane SINGLETON, with slightly differing details which would be explained by the fact that Victoria was part of NSW until 1851
NSW 1843, #V18433252 27A, registered Melbourne, New South Wales, Australia
Sarah J SINGLETON
Parents: Ralph Singleton, Jane
Victoria, 1843 #13559
Sarah J SINGLETON
Parents: Ralph Singleton, Jane
Birth Place: Brunswick, Victoria
There is are a couple of on-line trees which have photos of Sarah and James Douglas LANDELLS.
Would you like further information?
Judith