Do we have to get a permit to hold a child's birthday party here?

No, but show up early if the weather is nice, as it is first come, first served.

If you want a guaranteed pavilion for your party, then yes you do.

I don't think so

Any party over 25 people you do need a permit. That will save your tables and you will be able to show people you have that space reserved. If it's on the grass you don't need one.

First come first serve is how they do it there. So no you don't need a permit