My dad starting having trouble eating sandwiches. He would pick them up at the middle and everything would fall out from the bottom. I take parchment paper and make a little pocket for his hamburgers and sandwiches and wrap a rubber band around it. When he gets to the paper, the sandwich is usually small enough for him to handle.

He struggles with using a fork now; I just continue to tell him to stab down instead of sideways and it seems to help.