Hi Silas
The LDS equate Hannah & the variations of Ann on their data bases. I am no expert, but I have found little use of the name Hannah in Australia & wonder if she decided to use Annie (or others decided for her ?) after she came here. Thus said, it may be someone completely unrelated. Unfortunately none of the children appear to have survived - Have you found any descendants of Robert? They may have information re their aunt.
Trish