I would recommend an even feed food (walking foot), reducing the pressure on the foot & serging the seams after sewing.

You might also look into using a stabilizer. Either a spray on or iron on. It washes out when you're through and gives the fabric extra body for sewing. Also, the type of seam depends on how much of the seam will be showing. Google recommendations for how to sew chiffon without the raw edges showing through. Maybe a french seam?

Thanks Pris and Gram, I will be trying all. I redid a bodice with iron on interfacing on the lining it was better but now I will try your suggestions too. My niece is 5'4" but with a very small frame. A 24" waist so it is hard for her to get adult dresses without alteration or a try in the Junior department. Thanks again Elizabeth

Hi - I think hand basting is always a good idea - & I know another trick is to use strips of tissue - or other thin - paper to stabilise the seams when stitching, then tear away the paper when through. French seams are the traditional finish for chiffon, & I've also seen binding used.

HTH

I sew almost daily with chiffon and sheers, including making delicate tiny hems by machine. As you can imagine, I have tried many approaches and products to tame these fabrics. Here are my two favorites. The best, I think, is to use a product called "Sullivans Fabric Stabilizer." This is a spray-on in a metal aerosol can. My local quilting shop stocks it & I'm sure it can be ordered on the web. My procedure is to work with a block of fabric that is a little bigger on all sides than the pattern piece that will be cut from it. I put a piece of cotton on my ironing board to catch the excess spray, lay down the fabric block and spray it liberally on one side. Then (and here's the trick!), I pick up the fabric block, flip it over, and iron it dry, with a dry iron, so that I'm ironing on the non-sprayed side. This helps the stabilizer to penetrate and do its thing. The result is a fabric that is now easy to cut and sew without more slippage than, say, cottons. When I no longer need the fabric to be stabilized, I hand rinse it for a few seconds under the tap with a touch of baby shampoo, briefly wrap it in a towel,and then iron it dry without steam. The "destabilizing" takes about 2 minutes. This works so well that, for example, I can serge a tiny 3 thread rolled hem on the chiffon with no other stabilization and virtually without whiskers.
Second, if you want a removable, tear-away-like stabilizer under your stitching, I suggest using the wash-away Solvy, which is like a thin transparent plastic. You don't actually have to wash it away after stitching over it--it will tear away easily. The benefit is that nothing visible will remain in your seamline.
Hope this helps!