It is initially time consuming but worth doing.
if you have the recipe you just log the weight of each ingredient in the recipe bit, in the box top right tell it how many portions those ingredients make and it works out for you how many cals per portion, it saves it to your recipes for next time and logs it to your daily diary.
If the recipe is for 30 people it doesn’t matter, you don’t need to divide each ingredient yourself, just log the whole lot, say it makes 30 portions and it will tell you the calories total.
They must be tried and trusted recipes you are using with young people so you will be making/eating them again, only you need to decide if you want to eat a full portion!
dinner in general - you get used to sizes as you go along. I mean carrots & peas or mixed leaf salad - yes I log at home but I wouldn’t worry if out but I wouldn’t have coleslaw on a salad without portioning/weighing. Roast potatoes-well I know when I dish up at home and have 2 very small ones at most so know the weight. I would copy when out or have one large one. Meat, a couple of small slices 60g, heaped spoon of mash 150g..small spoon of gravy 50g but all this I know from logging and weighing at home. I know a portion of my home cooked lasagne is around 500g but a Pub portion with garlic bread could be 3 x the calories. My very small jacket potato of 100g is under 100 calories but baked potatoes when eating out are 3 x the size I would eat at home because they want you to feel you have had value for money so they are 3 x the calories.
I did have a wobble the first week thinking it all felt too complicated but I assure you, knowing how many calories you are actually eating, when you want to lose weight, is very worth worth knowing.
Hang on in there. It gets easier very quickly.