Same ages and both competed in horse riding. Their worlds may have overlapped. Still digging.
Obama’s Vineyard Vacation Home: Blue Heron Farm
http:// www.ibtimes.com/obamas-vineyard-vacation-home-blue-heron-farm-301451
Sarah Doyle, Maggie's trainer, runs Blue Heron:
https:// vineyardgazette.com/news/2008/08/01/stable-friendships-build-pond-view-horse-farm
http:// www.mvtimes.com/2010/11/25/chilmark-3568/