Don, have a listen to this track.
 
http://soundclick.com/share.cfm?id=12024980
 
All I had on this was the main vocal to work with. The singer was busy with school work and studies and did not have the time to accommodate me by recording 4 additional tracks.... 2 leads and 2 harmonies.
 
I cloned the lead (4 clone tracks total) and dropped them in low and used the thing Bitflipper mentioned..... I moved one back a few milliseconds and the other forward of the main vocal a few milliseconds.... I kept them low as described above.
 
Then working carefully and manually in melodyne, I used the other 2 cloned tracks one at a time and manipulated the notes that I wanted into the harmony parts.
 
It's not the ideal way to do things but if you work carefully, you can certainly minimize the artifacts and the comb filtering.

Another approach is a widener on the BGV group to get them out of the middle. I have also seen them panned at 50/70/90 for each vocal harmony. 100% L & R is reserved for delays and fx in a modern mix to keep things out of the center, unless a mono fx is used. This is a recent trend and not universal.

The "Nashville" approach for tracking background vocals is to triple-track each harmony part.
Roughly speaking, one take is panned left, another right, and the third is up the middle.
While tracking, session singers often want to hear the first take panned left in their cans (while they're recording the take that will be panned right).
This allows the vocalist to focus on and adjust to the nuances in the first take (to match closely).
 
With three-part harmony triple-tracked, you get that nice full/wide (group) background vocal sound.
 

Jim Roseberry
The "Nashville" approach for tracking background vocals is to triple-track each harmony part.
Roughly speaking, one take is panned left, another right, and the third is up the middle.
While tracking, session singers often want to hear the first take panned left in their cans (while they're recording the take that will be panned right).
This allows the vocalist to focus on and adjust to the nuances in the first take (to match closely).
 
With three-part harmony triple-tracked, you get that nice full/wide (group) background vocal sound.
 

For my last two efforts I double tracked and did some panning with each part.  I'll try a triple next time.  Track templates make this easy peazy.  I'm so enjoying all this.
 
Donny

Jim Roseberry
The "Nashville" approach for tracking background vocals is to triple-track each harmony part.
Roughly speaking, one take is panned left, another right, and the third is up the middle.
While tracking, session singers often want to hear the first take panned left in their cans (while they're recording the take that will be panned right).
This allows the vocalist to focus on and adjust to the nuances in the first take (to match closely).
 
With three-part harmony triple-tracked, you get that nice full/wide (group) background vocal sound.
 

 
I have not tried to do this yet on the BGV...... but I will on one of the future projects. I have to write something new first.
 
The nuances are something that has to be gotten right. Where the word starts, the phrasing and groove, and the endings of the words.....especially the words that end in "S"..... those things will stick out in the mix even when they are low in the mix. Nothing destroys the professionalism on the mix like hearing the BGV end the word in 3 different places.

Well last evening I did my first triple track on a part.  It was single line, tracked three times, panned center, hard left and right.  There was another two tracks an octave higher panned a little left and right.  It's on the intro of this tune:
 
https://soundcloud.com/donny-collins/carry-to-my-love-blessed-union
 
Only compression and low cut at about 200 hz on the lower octave.  Did one take of each track, took maybe five minutes.  Like it alot.  I've got a track template setup for my mic/pre, so it's really easy to add takes.  I'm sure there's an even easier way I've not used yet.
 
Copy that on the phrasing and blend...that is key and I'm careful about that.  That's where paying close attention in high school choir comes in really handy.

There ya go.... play around and have fun with it.
 
I tend to run the vocals pretty quickly as well. By the time I have gotten to the point of recording, I know the phrasing fairly well on most of the songs I write. So the recording of tracks and harmonies goes quick. But yes.... I have to pay attention to the details of word endings....

i love the stones' backups on the older songs...
 
and they RARELY said anything together!
 
LOL
 
so, just goes to show you, vibe always trumps dead-on accuracy
 
check out some of Rundgren's vocal panning on 'something/anything'
 
 

batsbrew
i love the stones' backups on the older songs...
 
and they RARELY said anything together!
 
LOL
 
so, just goes to show you, vibe always trumps dead-on accuracy
 
check out some of Rundgren's vocal panning on 'something/anything'
 
 

 
Agree 100% on the Stones and others like the Grateful Dead..... the vibe was raw and in your face.... perfection was neither sought nor achieved and that was the goal. And that's what made that music so special. Even their studio stuff was loose and free....
 
Not so in Nashville studio's. Dot the "I's and cross the "T's"....

yea, i don't really care for that stuff.
 
too stiff.