My year and a half old baby brother had his first horse back ride the other day :) My five year old brother (sitting behind me) rides with me regularly, so we just tossed Tom up with us.
NOTE* Nobody was in any danger, we hardly even moved. YES I am aware that no one is wearing a helmet, TJ usually wears one when we go off property but we were just hanging around in the front yard. Indie is child safe and knows her job very well, anyone can see how quiet and relaxed she is with them. And no we were not hurting her back, all three of us are very light weight, and she's never been sore after doubling.
Tommy even tried to turn Indie a little, the boys a natural