Family Reunion

We have a family reunion this coming Saturday. My Daddy's side of the family is quite large. Granny had 12 kids, and they all had kids, and they all had kids, etc. It's going to be a great day. I am very much looking forward to my kids meeting and playing with new cousins. The one issue at hand, is Miss Kira Jean. With her autonomic dysfunction, she cannot tolerate extreme temps.. her body goes haywire. If it's too hot, she runs the risk of storming. Jim says people will understand if she cannot be there, ( it is outside at a park). But that is not okay to me. Family want to meet Kira, and Kira wants to meet family. Period. Usually, if we attend a summertime gathering, it is at someones house, and Sis gets to be in the cool house. I am thinking, I will bring a spray bottle to wet her down IF she gets too hot. The forecast says it should be 86 that day. If all else fails, and she starts to "act up" I can leave with her. But I feel this is important enough that she needs to at least make an appearance. ? I would love if any of my readers have a special child who is sensitive to heat, what would/do you do in situations like this?