I think your idea would be great if you were just using various articles of clothing, pajamas, favorite skirt, jeans, etc. but if the parents gave you tshirts with designs, printing, sports insignias, school logos, I would go with the more traditional t-shirt quilt designs that keeps the main theme intact. Feline Fanatic shows an example a more fun setting than some. If you look here, search t-shirt quilts and google, you'll find more. Hopefully, you can discuss ideas with the parents once you have a plan in mind. It is very nice of you to do this for those grieving parents.