How about using something like a U87 to bring out some presence in her voice, or preferably something along the lines of a U67 to tone down the air? Something like a U47 might just sit on her voice completely but I've heard the Peluso 2247 LE used to pretty good effect on female gospel-ish stuff. Anyway, it sounds to me as if you need a vocal chain that accentuates the presence area more (or doesn't accentuate other areas as much).
If you're stuck with the recordings you have, I would just suggest raising the mids a couple of dB (any more will probably sound unnatural), and rolling off the air. The person before me is definitely right about the meaty 500-1000 Hz stuff, although I'd be tempted to look a bit beyond 1000 Hz as well. Bring out a bit of that meat and a touch (NOT TOO MUCH) of whatever presence you can find around 3-5 kHz, give or take, and roll off the air some and you should be fine.
BTW if the vocals are airy, you're probably not going to make them sound any less so by recording three tracks of them and having them literally left, right and centre. That's probably not going to focus them. If anything, I guess it would probably make her sound more like a little choir of angels or something.