If you're using ribbon then just hold a match or lighter to the end so it melts just a little and you don't have to worry about it fraying.

OK, I do garments (and sew for DG all the time - just a you I know how to make work for myself - lol). You can go to Joann's and pick up the new fancy zippers (they look like lace, very sweet), and sew it on "TOP" of the back. You don't need a zipper foot and it just looks like a design on the back of the dress (very simple). This way you can keep your seam allowances (without shorting yourself), with all of the big designers using zippers that show on the back of dresses your DG will be in style and you can keep your sanity too.

The problem with velcro is that the 'hook' side will be snagging any lace or delicate fabric it touches. What I would do is use snaps or buttons. You can add a strip of any fabric to one side of the seam, for the 'back' or underside of the fastening seam. Just make a facing, for one side, instead of folding it into the seam. This will extend it, so that a fastener can be attached and covered with the top part of the seam. I hope that makes sense.

I like Kathy's solution. Think about attaching a length of fabric behind the ties on one side and it makes it expandable.

You can trim the Velcro to narrow strips, also. You don't have to use the entire width.

Velcro does cstch on everything - and it probanly would snag the lace.

I would use snaps & stitch bows on where the snaps are so it looks like ties on the back.

A very easy way to put a zipper in a garment is the sew the seam together with long stitches. iron the seam open. Lay the zipper on the seam with the teeth going straight in the center. Pin or glue the zipper in place. Sew down one side of the zipper across the bottom and up the other side. Use your seam ripper and open the seam. You won't be able to get as close as with a zipper foot, but I have sewn them in this way with a regular foot and they looked ok.

I think you should go with what the pattern says. Buy a zipper and take the whole she-bang to a cleaners or a place that does alterations and ask them to put in the zipper. My sewing machine only made ugly buttonholes. I took a little GD dress and had someone make the buttonholes at an alteration place. It took her less than 2 hours and cost me very little. My dress was a hit! I have a new machine now. If I was close to you I would put in the zipper. Then you are sure everything its and is sturdy and plays well!