Your intent is loving, but make it definitely a comfort quilt! Having had a painful childhood due to a mother's mental illness issues, the last thing I would ever have wanted at the time of her death would be any reminders. Even now, years later, this is NOT something I'd want. A comfort quilt says "I care about you" and is not intrusive. Let your poor SIL have time and space and peace; not all relationships need to be memorialized. Give her a loving hug and a comfort quilt.