Bravo on the code Graham, I haven't tested it but I'm pleased someone else had a go at it first.

I was thinking it would be better to tag the dialog with a character style and then apply highlights to the words that get changed - I reckon I would want to review a lot of the changes before I would be confident that you can simply change the tense of individual words without ruining the content.

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Andrew Lockton
Chrysalis Design, Melbourne Australia