To have a method of changing the styles listed in the Quick Styles Gallery you would need to set up a series of templates and either:
1. Choose a template to attach and then refresh the styles from the template or
2. Save each template as New Style Set (on the Design Tab) and then choose that style set to apply to the document.

In either option, you are effectively importing styles from the external file in order to get a new set of style definitions which includes what you wanted to see in the list of styles and quick styles.

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Andrew Lockton
Chrysalis Design, Melbourne Australia