Always good to hear from a fellow researcher, thanks for your post. Happy to share any information with you, Esther Mary Brown was born in 1858 in Launceston, Tasmania, Australia. her parents names are John and Ellen Brown. Ellen's maiden name is a bit difficult to decipher but I have it down as MALAHY which matches birth details to Esther and marriage details to John Brown. Based on this detail I think there are 3 sisters and 1 brother born in this same marriage. I have attached a copy of Esther's and Wallace's marriage Certificate for your records. By Nellie, I am assuming you are researching "Nellie Emily Brearley" ? I have got the info on their marriage, date's of Birth, date's of Death etc if required. I can confirm that they had one child, un-named, who was born and died in 1917. BMD NSW has the registration number as 16874/1917, and I have the numbers for the rest of their key events if you need them. As to what the child died from, I do not know as I am yet to order the death certificate.
I also have some limited detail of Nellie's parents and siblings on my Family Tree on Ancestry.com.au if you are interested. If you would like access to the tree please let me know and I will send through an invitation.
I hope some of this will be what you are looking for, I am really interested in your research and look forward to seeing where your search fits into the family tree. Please don't hesitate to contact me if I can be of any further assistance.