Cut the brisket in half, in the width (you can ask your butcher to cut it for you or you can do it alone by laying the brisket flat, and with a sharp knife cutting carefully through the brisket horizontally).

Lay the two brisket halves and smear with duck sauce.

Pound the capons to tenderize, then place over the duck sauce and smear on a little more duck sauce on top. Top the chicken with the beef fry. 

Roll up tightly together to create a roll. To keep it secure for baking, you can either use cooking string and tie it around the roll, or you can use a meat netting roll (available on Amazon).

Layer the onions in a baking pan and place the meat roll on top. Mix the onion soup mix, duck sauce, salt, pepper, and chicken soup together. Pour it over the meat. Cover and bake on 350 degrees Fahrenheit for three hours. Allow to cool before slicing.