The easiest is to deconstruct the shirts and make quilts. I would cut 8.5 inch squares from the backs and put them together with a coordinating sashing of about 2.5 inches. For a 60ish x 80ish throw, you would need 48 squares, sashing in between and the same width border all around the outside. Backed with Minky or Fireside, it would be like a warm hug from your Dad.
I have also seen pillows made from a shirt. the buttoned front closes the pillow over the form. I have also seen aprons made from shirts. Here is one link. I know there are many.
https://www.allfreesewing.com/Refash...ns-Shirt-Apron