New information has come to light.

Isabella Forbes was the daughter of Ann Eakin Forbes and William Forbes, of County Tyrone, Northern Ireland.  Mother Ann was convicted of Larceny in 1849 in County Tyrone, and she and her two children Isabella (DOB circa 1836) and William (1849) were imprisoned in Grangegorman before being transported to VDL (Duke of Cornwall, 1850). 

Upon arrival mother Ann was incarcerated at the Cascade Female Factory and the children were admitted to the Orphan School 31st October 1850. 
In 1851 Ann married English convict Jesse Fisher (Maitland, 1843) and settled in Melville Street, Hobart.  In 1852 Isabella was released into her mother's care, and in 1854 married 31 year old Cain Jones, (Equestrian 1844).  Cain and Isabella had 7 or 8 children together, and resided at Port Esperance nr. Dover where Cain was foreman at Kent Saw Mill.  Tragically Cain was killed in a boiler explosion 25th January 1870.  13yo son William was critically injured in the same explosion and 10yo son Henry was killed.  Isabella was then assisted to move back to Hobart Town but was assessed as "peculiar, incompentent, a poor pathetic creature...quite silly, unsafe to be at large". 

There is some evidence that Isabella was intellectually disabled and indeed the couple's last child Margaret was profoundly intellectually disabled and epileptic, often an inherited condition.  Isabella and Cain's children were all admitted to the Orphan School through the 1870's.  In 1872 Isabella was delivered of her last known child Eliza, at the Cascade Female Factory, by then an infirmary, father unknown, although Isabella was using the name Hogan.  Eliza was later fostered out, but the writer can find no evidence that Eliza was admitted to the Orphan School at the time of writing, although this is highly likely. 

 Isabella continued to be admitted to various institutions throughout her life, and the last known record of her admission was in 1902, when she returned to the Orphan School Precinct as an invalid.  From there she was released to her oldest son William in the Huon in 1918, but died in 1921 in the care of her middle son George Jones, and his wife Celina, of Prospect.  George is the writer's great grandfather.  Isabella, Celina, and George Jones are buried in a shared grave in Prospect Vale cemetery, Westbury, Tasmania.