Im not sure exactly what I'm looking for guys or if it even exists.  I dont have any backing singers so do all the stuff myself.  Taxi screeners have advised me to either try learn to sing my backing vocals on maybe the third note or fifth instead of singing in the same pitch as the main vocal.   I can see where they are coming from.  There is no difference in the main vocal and the backing cause its the same feller...me.    I cant seem to sing on that 3rd or 5th note though.
Is pitch shifting the only option?  Someone told me pitch shifting can sound very fake.  Is there anything can be used to add an effect to your backing vocal to make it sound like it was in a different pitch.   Or is that exactly what a pitch shifter is doing?  Thanks all.   

Hi. Which version of SONAR do you have? The later ones include V-Vocal (up til X3) and Melodyne (X3 and forwards), which allows you to do this pitch shifting, and is specially made for vocals. But I would try (if you have access to one of those) to sing as close as you can to 3rd or 5th, and use pitch correction after that to achieve more of a backing vocal feel. There are probably free ones you could try if you do not have neither. Others might have other ideas.
All the best.
Edit: To my knowledge, pitch correction does what the title says, and corrects / alters pitch. Some are better than others, and Melodyne seems to be up there with the best (if not the best).

Try working out your harmonies with a VST synth. Then take out the root note, and sing along with just the harmony notes. You can track your harmonies using this technique, then just delete the synth when you're done tracking the vocals.

Hi Ken and Led
Thanks for the great tips.  I have X3 studio.  It's the very basic version of Sonar.  I'll look into the Melodyne.  I've only heard of it but no idea if its installed or what it does.  
 
Hey Led good idea.  I'll try sing along as you say with a synth or even a temp guitar riff starting on one of those notes.   I might mute the main vocal when doing this.  My own vocal is forcing me to sing the exact same pitch.
I take your point guys and I do agree with you.  If you can sing the vocal naturally it would be better. 
Thanks guys  :)
Xave

We are highly attuned to what the human voice sounds like, even being able to recognize someone by it. So yes, it quickly sound fake.
 
That said, if it's far back enough and there's a lot of other stuff going on, you can get away with it. What I find with Melodyne is that, if you shift a lot (a few tones) you get odd artifacts. But if it's pushed back, the character is still recognizable, so it will still sound like it's you singing.

Hey Ken..
 if you are pitching songs to taxi, you might be better off not adding background vocals at all. It's better to leave something off if it doesn't make the song/track better.
I had a good friend that became a top producer in Nashville back in the 90's. He would put out the word for songs to all of Nashville, and have literally a garbage can full of cassette tapes to go through.
If the recording sounded amateurish in the 1st 15 seconds, he trashed it.
If you need background vocals, you might try Fiverr.com and get someone to record them for you cheap.
To practice for your own benefit, work on adding backgrounds to your songs, just don't use them in the final mix if they aren't good. Eventually you'll get better.
Sing along with records that have harmony, such as certain country songs or old Beatle songs...lots of good harmony there.
Also, keep in mind, a good background vocal is not always singing with the lead up a 3rd and 5th
There is an art to singing background vocals, and it takes a long time to learn how to do it well and create good background vocal parts for most people.
I have worked in the studio with singers that have had hit records, and some just couldn't sing background vocals at all...they were just used to singing with their feel, like behind the beat, and a little more loose.
Anyway...that's just my humble opinion,....hope it helps :)
 

Leadfoot
Try working out your harmonies with a VST synth. Then take out the root note, and sing along with just the harmony notes. You can track your harmonies using this technique, then just delete the synth when you're done tracking the vocals.

this is exactly what I was going to say.
its really not that hard and if you want to be a better singer, learn to sing your harmony's.
the 3rd + 5th are most popular.
get a synth and try your best to play your vocal part (the main melody)
then play the 5th note in the major scale to this synth line/record both lines.
practice this 5th melody, then sing it while listening to your main vox line.
 
you cant miss it man, when you hit the harmony correctly, something inside your brain kicks in(serotonin)
and the endorphins will let you know where to go from there
 
as funny as I made that just sound..i swear its true.
hit the harmony and you will feel it. it will also make you into a better singer.
by learning harmony's it forces you to become more accurate in your pitch.
 
now...where to place those harmony's in your song...that's a whole different talent.

I have a friend that has a good voice but just can't sing harmony.  He always slips back into the lead melody after a line or two.  So, I had him learn the phrasing of the lead vocal to a T, then I muted the lead vocal and had him sing the harmony part as if it was the lead vocal.  He could do that just fine, and when I added the lead vocal back in, the two parts were in sync and in perfect harmony.  Anyone can do this if they have good timing and the song lends itself to this procedure.

I write all my harmony parts out in advance using a piano vst
 
The different lines are on  separate Midi clips but each one is linked the vsti.
 
This way, all I have to do is mute the clips the vocalist does not want to hear and she can sing along to the "live" clip
 
 

Taxi telling you to add harmonies seems a little odd.  I'd think you'd only add harmonies where harmonies were required by the song.  Duh. 
 
As far as vocals, nearly every vocal you hear has been doubled (sang the same notes twice and dropped the double back in the mix).  Sometimes I will even double the lead vocal twice, and pan them hard L and R, and back them down in the mix.
 
In the last song I did ("Brain Grinder" youtube link below) I also did the +/- 3, 6, 9, 12 detune vocal fattening trick by cloning the lead vocal 8 times and pitch shifting.  Although my Aux-fat track it is pretty far back in the mix, it was noticeable when I turned it off.  So I think from now on I am going to add that to my standard bag of tricks.
 
When it comes to harmony, other than hitting the right notes scale-wise, I always double each part and do the LR pan trick.  For 5 part harmony (I'm a singer - my granny sang with the Met) that winds up being 10 tracks, and a lot of sweat and body odor in the vocal booth.