abc123xyz

My daughter in law brought me a lap quilt that she had purchased at a local thrift shop. The front of the quilt is a chenille type material and the current backing is heavy flannel. She does not like the color of the backing and has asked me to replace it with velvet in another color. She ordered the material and it is a silky velour type that stretches in one direction. I need tips about replacing the backing with this material. I have torn the quilt apart and there is batting between the layers. I would replace this but hesitate as it is sewn to the top in very small stitches and I am wondering if it might be best to use what is there rather than to try to remove it. I am wondering if it might be wise to make sure the batting is smooth and to cover it with a piece of thin white cotton material to hold it all in place. I plan to try to sew this all together with my walking foot. Original was sewn in birth style and turned. I aim to do likewise. How do I hold the backing in place when measuring and cutting and how much stretch do I allow? Should this be spray basted or will pinning/basting be sufficient. The original was not quilted and I am wondering if I will need to do so in order to keep the new backing in place. Any and all ideas and experiences are welcome. This should be a simple task if the backing were woven material but the stretch scares me a bit.