Maybe you could try a revamp for your whole family's menu?
If you focus on meeting daily fibre target, that puts veg & pulses ahead of carbs - which goes a long way towards fullness & not feeling the need to buy extra food 'out of the house'.
I've heard people can get some quite useful suggestions for meal plans using chatGPT & tailoring the suggestions by tweaking the prompt to meet family flavour & ingredient preferences.
Generally speaking something like
breakfast - oats, berries, seeds & 0% yoghurt
lunch - pitta or lettuce wrap with tuna or chicken & lots of veggies (carrots, peppers, small amount of avocado, beansprouts, mushrooms, lentils etc lots you can mix & match) focus on vinegar/pepper/hot sauce for seasoning not buckets of mayonnaise or oil based dressing. Doesn't sound like much but with lots of veg, can actually get challenging to finish.
SNACK - important to not reach for chocolate bar/crisps! Hummus & veg or apple slices w peanut butter. Must have some protein & fat or won't last. Protein shake option in a hurry.
Dinner - quinoa, brown rice or wholemeal pasta or pulses as base carb, but ONLY 1/4 of plate. Fill half with veg eg green beans, sprouting broccoli, leafy greens then 1/4 plate of protein & sauce (swerving butter/oily/cream based sauces).
Weekend breakfast/any meal swap shakshuka eggs with beans/tomatoes/spinach or huevos rancheros wrap with eggs & refried beans & peppers or fried eggs on puy lentils with salsa verde.
Emergency cupboard meal. Tinned bean soup with some veg sticks. John West tuna salad bowl. Poke bowl (ideally brown rice or quinoa not white rice).
Emergency snack. Pint of milk & an apple.
If the whole family did a variation of a meal plan based around broadly this for a month, I guarantee you'd all be healthier, almost certainly be sleeping better, and if you combine it with a decent amount of walking & the odd few press-ups & pull ups (under the dining table, keeping most of your weight on your feet until stronger), I'd venture to suggest every single family member would notice some kind of change in body composition!
The NHS has a really easy strength program/podcast that is easy to build into a morning or evening walk if you want to do that together with your daughter. Search
NHS Strength and flexibility
on your podcast provider. Or more at https://www.nhs.uk/live-well/exercise/
It will be much easier to help her/bring her along if you all make the commitment as a family to do the same things. It's unlikely to be bad for anyone, even if they're already a healthy weight & body composition, and will be a huge boost to moral support & commitment for her if she's not the only one on a restrictive 'diet'.