This is very good advice. In all the supervisor/management classes I had to take over the years. They always said to complement before criticize that way they would be more open to suggestions for improvement.

Does she come to your house to drop off & pick up? If so i would invite her over for tea and show her the quilt on the frame. Easier to show than explain.
Having said that, I don't quilt for a business, but do quilts for friends and family. I've done several for someone who should know better, but has given me tops in the past with wavy borders. Somewhere on the board I read that quilting a piano key will take the fullness out. this worked for me. It's a bit of work because it's not a continuous design and you have to measure. I start in the center, and stitch the first 'key' down, matching centers of top and backing. Then the edges then half way between those quilting lines, each time measuring the centers of top area and backing. Basically you are doing an easing in process. I continue until the keys are about an inch apart. Another down side to this process is that I have to turn the quilt as you really can't do the sides this way (well, I can't anyway). Might not be the solution for this quilt, but it's a good technique to know.

Of course there's always the amazing quilters. Look at this video:

http://www.youtube.com/watch?v=lPHsBYa36W0

This is what I do as well. Depending on how badly it looks and how much you like her - I might be tempted to do it myself. I do not usually do work for friends but recently I had the exact same problem. I used an old clothing trick to evenly ease in the fullness. Loosen your tension then stitch a running stitch just inside the outer edge (about 3/16") then gently tug on the bobbin thread and run your fingers up the stitch line gently to just tighten the stitches (not enough pressure to gather the fabric however). Works great for small amounts of fullness and bias edges. Also works on individual blocks.

When I have fullness, I place 1 can of vegetables on either side of my longarm needle. (Green beans are what I usually use, but that doesn't really matter.) The needle will not hit the cans as they roll as you quilt. I have been able to ease in a great deal of fullness this way, but not always all of it. If I have to take a tuck, I try to line it up with a seam in the body of the quilt and it seems less noticeable. I know what you mean about not wanting to tell an older lady that she is doing something incorrectly. I quilt for a 88 year old and she does beautiful embroidery, but her borders are almost always wavy.

You really do need to mention it to her especially since her other piecing is wonderful. Maybe you can say how you just saw this on youtube or a friend had pointed it out on one of yours and you want to give it a try. I would have her come over and see the fullness on your frame - you just don't see that when you are ironing.

I can feel your pain on this one. I have 2 little sweethearts that have me do their quilting. Yes, their borders wave like there is no tomorrow. I use beadboard or piano key on the borders. I cut another piece of batting and place it under the borders of the quilt and then quilt. I do not baste the edge until after the quilting so that I can manipulate the fabric. If there is just a bit of wave to the borders, I do not add the additional batt but do beadboard about 1 inch apart. This usually will take care of the waves. When using the additional batt then I beadboard about 1 1/4 to 1 1/2 inch apart. Good luck and hope this helps.

Thanks everyone for the helpful ideas. I watched that great video mentioned by PaperPrincess and, thankfully, these borders aren't anywhere near that wavy. What she did on that quilt was amazing. There are 3 borders: 2, 4 and 6" so I really don't want to tear all of them off (but that's probably what it needs) and because she's such a sweetheart I don't want to call her up to come get it and redo the whole thing so I think I will go with the piano key/beadboarding idea. Wish me luck and I'll let you all know how it turns out. I like Crashnquilt's idea of an additional piece of batting too. Not sure if I need it this time, but I'll remember it for next time.

Pam, I am also a senior citizen and would like to know, if someone is doing my quilting, that there are problem. She may not realize that there is a problem, and can't fix it if she doesn't know about it. Offer to fix it for her at a price, ask her if she would like to fix it, or let her know that if nothing is done there may be pleats and tucks in the borders. If she is not sure how to fix it, maybe you could give her a little bit of instructions. Make this an enjoyable experience for you and her.

We have the same issue with our guild when we do group projects. The members know the right way to put on a border, but the "start at one end and sew" method is faster and they seem they don't want to bother doing it the right way when it is not for them, and they don't have to machine quilt it. They know the right way, but yet they still do it the "quick" way. It is so frustrating.