I have a document where the built-in style "Default Paragraph Font" has been set to a particular size. It shouldn't have a size - it should be inheriting from the paragraph style (that's the whole point of the style).

If I go through the user interface, I can't modify this style (the modify button / dropdown is greyed out)

While I can work around this in most places, it creates problems for the Table of Contents in particular, as that is forced to be in this style and it overrides the font size from the styles like TOC 1 (etc).

I can set the font size through VBA -

ActiveDocument.Styles("Default Paragraph Font").Font.size = 10

sets it to ten point, but I can't work out how to reset it back to inherit.

At the moment, my table of contents is set to be all in the same size, but really TOC 1 should be bigger than TOC 2.

Does anyone have any suggestions for how to fix this?

One approach is to use the organizer to copy over the style from a working document, but ideally I'd like a way to resolve the problem without doing that - especially as that's not an easy approach to automate.