Food hoarding-claims it's not them

Allow them to eat in their room. They may need that due to previous situations tell them it’s okay so they don’t feel something will happen to them. Hiding/ hoarding food is often a sign of neglect or just finding the snacks as a luxury. Eventually you can put the boundary back up but for now they may need the opposite.

Maybe I’m looking too deep into it also

If you want them to not eat or have food in their room then I would check it once a week ish. Give them a shelf or basket in the pantry that has their food and snacks in it. And let them either freely get it or say like once a day they can have a snack. But that those are their snacks and no one else

Let them keep some snacks in their room and ask them to eat them outside of their rooms. My youngest sister is adopted and did the same thing my mom’s solution was to designate a drawer in her closet for chips and other non-perishable snacks and it helped a lot. The biggest thing is she needed to feel like she had 24/7 access to food to feel safe

we have a labler. we split.all.the snacks evenly.and label everything. which could help. because then everyone knows and eats their snacks at their pace.
also you may have to lift the rule a bit due to the trauma . but maybe have a limit. like you can have certain things in certain moderation. but you have clean up and be responsible to keep this rule.
when my kid got older the later became the rule