Bring a poncho in case.. some rides will be wet too. Went last Halloween for HHN but I sat outside throughout Coz the rides are no-no for preggies. Most of the rides are not suitable for your 3yo & infant as well. So you might need to wait for your older kids outside with them. They are pretty strict with height requirements for your 9 & 8yo as well. Hope these help!
oh wow! big family! only brought my kids above 5yo which was ok. all the best 💪