If they cover a group of notes on the “oo” sound, you would normally use a word extension. A hyphen would be a break between syllables, like hy-phen. Can you give us some more details on what you are doing, and possibly a picture?

Thank you for your response, Mike

Well, after I pondered a bit more--which I should have done sooner--I realized that the hy-phen, either by typing it or using alt+0173 does not bode well in the Lyrics.

However, the "N" dash does, which is alt+0150.
So, using Control+space to enter a space interwoven with the "N" dash solved my quest.

The "M" dash (alt+0151) is two long for my purpose, but certainly could be used, also.

:-)
Vanessa

You might look to see if Windows has a shortcut for the n-dash (hard hyphen) like it does for the hard space. The Mac does.

For Mac users, the n dash – is Option dash; the m dash — is Option Shift dash. 

As a singer, I agree that the word extension is correct for most uses including melisma. OTOH, if the melisma is a series of notes followed by rests, I can see using n dashes — I would know what is intended. Any other use would likely to be confusing. Still the word extension is preferred and and publishing house editor would likely point this out. 

Ah!

So, on Windows, Control + Numberic Keypad minus sign = N dash.  Ctrl+Num -

and Control + Alt + Numberic Keypad minus sign = M dash.  Ctrl+Alt+Num - 

However, my intention is not the conventional melisma, or anything similar.

The "N" dashes -- in multiple -- serve my purpose.

Thank you, though,
:-)
Vanessa

>The "N" dashes -- in multiple -- serve my purpose.<

At the risk of being a gadfly, does it serve the interest of those performing your work? 

Don't hear that term much, any more, but no worries.

I am not using the dashes in the conventional way.

:-)
Vanessa