I am interested in what quiltingloulou said about quilting the borders separate and then attaching, but how do you attach them to the quilt?

Probably with a QAYG (Quilt As You Go) technique. I found this website that shows one method:
http://www.thequiltingedge.com/2011/...g-borders.html

With the above method, you do need to be careful to leave enough area unquilted to be able to attach the next border.

Yes, it is using the QAYG method. I just left a small area particularly on the inner side of the border in order to attach to the main portion.

In the quilting process the pieced(top) will stretch ever so slightly, while the back, being primarily a whole cloth does not have that stretch. Cut a square of fab the same size as block and pull on both.....there will be more " play" in the pieced block......this is the reason L/A ask for larger back......and the more intense the quilting, the more the back is pulled in. So, although, I have never put a border on the back, nor have any of my clients, actually I would not attempt doing that for myself or others. I would suggest you make you center smaller and you border bigger...the
beauty of the quilt should be the pieced side.

I hate when that happens. I put a border on my backing . When I started sandwiching I forgot I needed to make sure the borders needed to be together. After quilting I noticed it. Second time I messed up a quilt like this. I am going to stop piecing backs like that. Since I give most of my quilts away I am going to ignore it. No fix for it now that it is quilted.