I'm actually Raema's son and have an interesting anecdote to your post above – it makes a lot of sense that 'Levis' would be spelt 'Lavis' in England if you pronounce it in a heavy French accent.
Le in french sounds more like 'Lay' rather than 'Lee' so it would sound something like:
Given that most names were written down by priests / officials and often spelt differently (evident right up to when convicts migrated to Australia) it's easy to see how the phonetics could have been misappropriated.
Of interest, when I was living with a few French people a while ago they laughed when I asked what 'Lavis' meant in French – 'La' is the and 'Vis' is screw. It has the same connotations in French as well as English :o)