If you eat quickly you can get more food in before you're brain tells you that you're full. Ordering/making more food than you think you can eat and eating it quickly should do the trick.
Eat with like minded people. Eat with people who are happy to just eat and not complain about gaining weight. You’ll be sure to eat more than your usual without you noticing.
Ditzy: If you get full stand up walk around a few minutes then sit down and eat more.
Yes, do that. Works great. You can also do a few chores like putting the plates in the dishwasher, clean up the table or water the plants. The movement lets the food sort of settle. And most importantly: having done some chores calls for a reward (like some extra dessert) doesn’t it😀