Was someone talking about making a separate bottom to go underneath? Something you can lay down first and use inexpensive fabric for the width of the quilt and then quilt a border on the 3 edges of that the length she needs. Then you won't have to mess with your nice quilt. She just has to pull up your quillt and lay the first part of the quilt (which could have one layer of muslin in the middle with the edges bordered) and then lay your quilt on top of it. Is that stupid? Because I think that is what I would do. It would be super easy. She would have to pay for the muslin, but you can get that at
www.fabric.com for fairly inexpensive or somewhere else online and not injure your original quilt.