Thanks all, that's sort of what I thought (that the discount was only for adult residents), but I figured it'd be a shame to not ask and then miss a discount.
And for the record, I wasn't trying to get away with anything! I was a FL resident for most of my life, so I know that it's not something you can try to fake or slip past. I just figured since the girls ARE Florida residents, they might qualify for the resident room discounts. (And since they're not adults, they don't have the normal FL resident ID, so that's why I was asking what you could use for kids, if it was possible.)