Yes you are able to reserve with time
Yes you do have to reserve if you want a pavilion . A single table or a couple moved together you dont have to.
Its probably better to just show up a few hours early or in the morning and just have someone sit and keep it secure for your event. Or even just decorate and post a little sign, Suzies bday 4pm or something like that. I dont know if theres a number you could call, it's just as easy to do this.
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