They have it posted no outside foods or drinks but I've taken in water bottles and they are fine with that.
Individual portions haven't been such an issue, and if it is there is a cafe a few doors down where you can sit outside and finish before rejoining your group. Just ask and be understanding.
A sign says no outside food or drinks, but they let us bring in a couple of bottled waters. They do have a few food and drinks inside for sale with an area to sit and eat.
Thanks! Your answer is awaiting moderation.