Since you've never made a quilt, I'd like to suggest you start with something easier, than sweaters and other irreplaceable items. Get yourself some cotton fabric and learn the ins-and-outs of piecing and quilting, first. Quilting with those sweaters will be a bit trickier, so it's best to learn the basics, first. Maybe you can find some fabric that reminds you of your dad . . . or something you think he'd have liked. Use that for your very first quilt, so that if there are any problems, the precious items won't be harmed.
Welcome, from Texas!