I'm going to go against the grain here about the whole concept of "treat foods" and question whether children should have free unfettered access to ultra processed food. I'm an adult who has issues with food and has had to use WLI to get that under control. I've also been through it with DS2 (now 16)
I can't allow UPF crap into my diet, because over time, the combination of what's in it plus my brain chemistry will create cravings, increase my hunger and reduce my ability to regulate my food intake. DS2 (who is also AuDHD like me) is similar to me and your DD and if that food was around, no matter what we did, he couldn't self regulate with it. He's into competitive sports now and has had a lot of education from his coaches about performance nutrition, so his attitude towards it has changed. In fact it was because he wanted to change his diet to help his sporting performance that we started changing what came into the house and really realising the effects for ourselves. DS16 realised for himself that he would eat that sort of food if it was there and had no off switch. Coming off it, for him and for me, was like a detox of sorts, both of us like bears with sore heads. DH and DS1, who don't have the same wiring (autistic, no ADHD and neither have these same food issues) were utterly confounded by it as it didn't affect them at all.
I'm no longer on WLI and as long as I stay away from UPF, I have no issues with overeating, but as soon as I start letting it creep back in, the same problems start reoccurring.
If your DD has a problem with this type of food, why buy it? Does it need to come into the house at all? Our bodies don't need this ultra processed crap - it's not a treat, it's fake food that's manufactured to be calorie dense and hyper palatable and it is deliberately designed to be overeaten. If this food has a negative effect on DD, you as the adult can choose whether or not you have it available to her. I honestly wish I'd just stopped buying it (and eating it!) when DS2 was younger and we were in utter despair over his sugar craving induced tantrums. Didn't matter what we did or what system we introduced to moderate it, if it was there, he wanted more, more, more.
If others in the house want to eat it and don't have an issue then it's harder though, everyone has to be on board. In that case, you could opt to buy single serve packs of these foods only and once the one portion is gone, it's gone.