Answer :
Base on the scenario, the child that you could infer as the middle child is Kyle. It is because Mark helped his father in packing the family van in which the eldest child should do because he or she is older to his or her siblings and in a way that he or she can manage to help his or her parents while Tara is likely to be the youngest because she is in need of assistance as younger siblings always do because they are still young. That leaves Kyle as the middle child.