Could not include photo in original. Left is the front of the fabric, right is the back side.

How do they hang? Do they have a rod pocket? Do they use clips?

One thing that I did one time that might work for you, might, just might.

I wanted some more width to a couple of panels that I had made and what I did was to construct a finished strip of a nice print that I felt was beautiful. I made this strip about 6' wide, finished.

Then I realized that I had an assortment of very large, beautiful, and vintage mother of pearl buttons.

So, I laid the finished strip onto the side edge of the panel to overlap about an inch or so and then tacked the strip to the side of the panel and sewed a nice button on top of each place where it was tacked.

The panel was a nice plain weave of real linen and the strip was also a piece of printed linen. The combination of beautiful linens and the big vintage buttons were a real charm.

I really liked this idea and you could always change out that one element of the curtain panel by sewing a newfrom some other fabric.

You could to something like this on the bottom, or top, of your curtain panel.

To add to the length you could attach such extensions to peek out from behind the bottom of the panel and appear to be an under layer. You could slip stitch it onto the backside of the hem.

Or, you could just sew this extra length onto the bottom of the curtain much like a border. Just be sure to line it and treat it as one with the rest of the panel, and it will look more intended. If you create a hem border be sure to create a proper 3" double hem and that will give you a more finished look.

You just would have to agree with yourself about adding an extra element of fabric to your panel. I know that it was not your intention to add anything, but, if you are opened to the idea, you might want to consider adding extensions.

It could match some other textile element in the room, perhaps.

I love the idea that it can be changed out if the room decor changes, if it is only tacked or hand stitched into place.

Otherwise, you seem to be on the right track to open up the hem and face it with a narrow seam allowance. But, if you don't have enough to do that, you might want to consider leaving the hem in place and adding a decorative piece as a border at the bottom. You might not ever get that crease out of the hem when you open it up.

Just a thought. I really liked the way my ad hoc extension turned out. Those old buttons were really a conversation piece. Most of them are about 2" or 3" inches in diameter. They came from husbands grandmothers button box and probably date to mid century or slightly before.

Sometimes the best thing to do is to not try to hide the fact that something was altered, rather make it an added decorative element that is valid in its own right.

I have seen panels that have added lengths that are quite long, like 12" or more and they are done well and look like they were intentional.

Just a thought to consider.

I've seen that done at the bottom, and I know it can look nice. But I don't want to go that route with these.

The ones I need to lengthen were purchased to coordinate with some other drapes in the center of a wide expanse. It was very hard to find anything that went with the first ones. The odds of my finding yet a third fabric of the right weight, texture, hand, and color to go with them are next to nothing. I've been through 2 fabric stores already.

Facing is my last remaining option. I'm getting fried and need to finish this up.

I'd probably use a drapery lining, but if you don't have any, maybe you could double up the muslin.

I went through everything I had and found some polyester lining. Very thin, so it doesn't seem to affect the drape.

Thanks to everyone for your help!