Advice on a few 4 and 5 yr old behaviour issues

[Yogafire]

DS is 5, DD is 4 (16m apart), and we have a toddler aged 17m.

The older two know how to behave (as in the boundaries we have set) but when we are outside our family setting, e.g. at a social gathering or when we have guests over, it seems like a free pass and everything deteriorates - possibly because they know they can get away with more. I know many kids go a bit wild in these situations, but it seems ours are especially difficult to manage in larger groups. Anyone got experience and advice on this?

Also, DD asks for food constantly. When we are at home it isn't so bad and we have a rule of one snack mid morning and mid arvo (banana/apple/carrots, which just about works, so long as she doesn't catch sight of food on the counter. But again at other people's houses the food requests are constant.
Anyone else have this? I don't think its hunger because she can be distracted from it, and i know how much she eats anyway. But then I do wonder sometimes is she just constantly hungry and what to do??

Any advice welcome.

What sort of things are they doing that's bothering you? As for the co start requests for food, have you tried upping her protein in the snacks? At 4 she's still growing and could genuinely be hungry.

Just things they know they shouldn't - like making a needless racket (noise for the sake of noise), taking or touching food in the kitchen or on the table before time to eat, playing messily (e.g. tipping all the toys out and making a big mess and not tidying up after themselves).
These are examples from today but the unruly behaviour in social situs is a common theme. They are ok at home, with the usual dose of sibling rivalry and a few off days.

More protein - DD eats a lot at meals! Plenty of protein too. I guess I could make the snacks from protein-based. It's almost compulsive. She cannot see food without wanting it. At friend's bday parties she eats rather than plays! She is slim tho. I'm not worried about that, just the constant asking drives me potty

Most of what you say sounds pretty normal to me. At that age they both really need constant attention when out and about. Exhausting I know.

Yes, if she's slim and is asking for food she's hungry!

Poor starving girl! She eats more than anyone in the family. I guess I just have to run with it but it drives me mad, constantly asking for food, even straight after lunch.