Have you ever written a script? Which language did you use? Can you use your experience to guide you with a solution like this:
Because of nested and grep styles, it might be necessary to look at every character and capture the properties of interest into an (potentially enormous) array and then walk through it looking for the changes that interest you.
I think it is possible from a plugin.
You will need to look at ITextCommandPreProcess and ApplyOverridesPreProcess. Or the post process equivilants.
This is a feature we are thinking of adding to one of out plugins.
Thanks to both,
Without plugin which is possible in scripting. Plugin development is new to me.