The Fox in the flowers/grass/vines fabric is fun, and if you want to bring it into the mix, using it for a pillow on one of the solid pieces of furniture may be a better location for it. You risk de-valuing the chaise, by pairing it with another leafy pattern very close in scale, but not the same, as if you tried to match and missed. By using it as a pillow, you pick up the connection with the natural world, and add the fun fox, perhaps with a brush fringe in the color of the chaise fabric, and can then find a new fabric which complements your grandmother's chairs and partners better with the chaise. There are a lot of wonderful fabrics out there.