This would be an adorable picture to take, but I absolutely would not take them trick or treating. It sounds as if you've already made up your mind to do it, but heres a few reasons right off the top of my head why I wouldn't.
*It would be too stressful for the birds.
*Its a biosecurity risk for your birds & your neighbors birds.
*Unless you're going in the afternoon the chickens will want to be in bed.
*You will have bird poop everywhere.
*Struggling with birds will diminish the fast paced fun of trick or treating.
Last but not least,
*Props are heavy. Even the lightest props get bulky & cumbersome quickly. Most people don't even notice the props, so its best to take pictures with the cute props & the cute shoes & then leave them at home. As a parent of three, I guarantee your DD will not miss them once she's out there & she will have more fun without them.
This is a time of year when most people go out of their way to keep their pets extra safe. Not trying to be Linus' wet blanket here, but I hope you decide to leave them at home.