Quoting Ms. Barnhill:
This is not perfect, but it is the only way I can think of to approach the
problem.
1. Type "The Florida Keys" and format each separate word with a double
underline.
2. Enclose each separate word in parentheses.
3. Before each word in parentheses, type EQ \x \bo.
4. Select each phrase, one at a time, and press Ctrl+F9. This will give you
three fields such as the following:
{ EQ \x \bo (The) }
5. Select each field and press F9 to update and toggle the display (or
Alt+F9 to toggle them all).
The EQ field with \x switch puts a box around a word. Adding the \bo switch
puts it just on the bottom. Adding this single line to the double underline
you already have gives three lines, though they're not quite the same
length.