Outlined text reacting to font size adjustment?

I need to create a single non-editable word inside an editable text - still with the ability to scale it proportionally with font size adjustments. My first thought was to outline the word, but this makes the word an inline graphic file that doesn't react when the font size for the complete text is changed.

Is there a way to insert and anchor an image or outlined text into a textbox - AND to control scaling with font size setting? This could as well be an image that locks to exactly e.g. 4 textlines and has to adjust if line spacing needs to be adjusted.
Additionally an advice to refere from outlining the word but in another way to make that single word un-editable yet to react to font resizing?