Freeze Composition is a free and easy to use Adobe InDesign script that freezes the composition of the selected text by using the no-break attribute and soft returns.
Freeze Composition also allows for scaling of the glyphs (ugh!) in case you add additional text to the line.
Installation: Open the "Scripts" panel in InDesign, select the "User" folder, select "Reveal in Finder" from the drop-down menu on the top right side. Copy the Freeze Composition script to the "Scripts Panel" folder in the opened window.