She doesn't eat snacks because she is hungry but because it is an habit or out of boredom, so the point is not the type of snack but stopping the snacking full stop.
I am French and live in Australia and still after all those years I don't understand why people eat all the time, everywhere, adult carrying food in bags, cars, even for a simple walk to the Parc.
In France, we have breakfast, then nothing until lunch around 12.30-1pm then a seated afternoon snack (can be fruit, biscuits, cake, yoghurt) at 4pm then nothing till dinner around 7.30-8pm.
The stomach doesn't need to be full all the time. It is ok to feel hunger which is very different than cravings but are caused by addictions to certain food.
In our home, we only eat in the kitchen or dining table. No food in bedrooms or lounge, only water. You could do the same in your house. Blame the crumbs or stains to say enough, we only eat sitting down together, and only 4 times a day.
Also, when the biscuits , crips, chocolate are finished, don't buy more. Don't buy the industrial white bread but a dark rustic one, then even if she sneaks in the kitchen, there won't be much to pick from and she will slowly lose the habit.
It has nothing to do with weightloss but detrimental eating habits. Nobody needs daily crisps or oreos and they have no place in a healthy life style. Of course there are biscuit or chocolate from time to time, but not daily.
The contrast is so evident whenever we go to New Caledonia, when you see French families, reading, sunbathing, chatting on the and then you can tell a cruise ship has arrived because families have those gigantic bags of crisps, of savoury cracker or biscuits, which they bought in Australia to eat during the cruise .