We usually have a just walk up to line CAst Member and tell them we would like to do child swap, they hand us a child swap ticket and one of us rides then, and then once they are done riding, the one of us that hasn't rode can then ride without waiting in long line again.
And if kids want to ride with each of you, they can so you don't miss the experience of riding with your kids who are old enough or tall enough... It allows both parents to ride with kids and kids get to ride twice...while the other parents stays with baby or kids who can't ride yet.