Could I get some help with catering my own party? Perhaps someone that likes math and/or cooking for a crowd?

I’m throwing my hubby his 40th birthday party. I have about 50 confirmed guests so far, not counting children (there could be up to 15 kids there, but there’s no telling)

The main entreé will be open-faced pot roast, mashed potato, and Guinness gravy sandwiches.

I’m making the bread in my bread machine. A two-pound loaf will probably make ten good-sized sandwiches, or 20 kid-sized portions. That’s the easy part.

The hard part is figuring out how many pounds of potatoes I need to make. How many potroasts? How big a portion of each should go on a single person’s sandwich?

I want to plan enough that I don’t run out if a few people go back for seconds, but I also don’t want to be eating leftovers for the rest of my life. ^_^ I’m also planning an array of appetizers, a big batch of vegan chili for the non-carnivores, pasta salad, and some sort of vegetable.

Thanks for the help!!