Also thank you Shume and Lucy 2. You're right, it's taking some sorting out!
Lanthy was her grand daughter, daughter of Christiana's son Ian Maydwell (who started life as William I'Anson). I've spoken to Malcolm I'Anson and he is a mine of information. One thing he showed me was an article his mother (Helen Maydwell) wrote in the 1990s for a paper called the Black Country Bugle (the Black Country being an area of the Staffordshire in the UK, which is where Isaiah Oldbury was initially located). She mentions Tasmania and the fire in the article. Some of her account isn't quite right (only discovered more recently as her account was obviously from memory and family stories and we now have access to many more records than she could look at) but it's mostly very minor things, so I can't imagine the whole Tasmania "adventure" was a mistake.
I hadn't seen that account of another fire you mentioned, obviously once Christiana had settled in Sea Lake. I'll see what else I can find on that. Disasters seem to follow her, flooding in Christchurch, fires galore...
I think at the moment that the comment about Armstrong was a mistake, looking back we can find nothing on that now. Her daughter Irene became involved with a man who she spent years with but never married. But his name was Johnson...