I concur with all who have recommended taking this apart and starting with the completed top and finishing with a method the new quilter is comfortable doing. BUT FIRST, please tell the person who is asking you to finish this about your frustration with how the quilt is now and the finishing. The top is great but the owner should know the quilt as it is now presents some problems for you and what the finishing might require. The "fix" should not be a complete surprise to her. The top would still be the original. Perhaps the owner wants it to be all original and would rather have it as a UFO but, if she wants it finished, give her some options on how it might look if you do it with your own methods. It lets her have some input on "making the quilt" her own, too.