Chevrolet 2006 Express Van Owner's Manual page 38

Q:
What if a child is wearing a lap-shoulder belt,
but the child is so small that the shoulder belt
is very close to the child's face or neck?
A:
If the child is seated in a rear outside seat position,
move the child toward the center of the vehicle.
Also see Rear Safety Belt Comfort Guides on
page 1-27. If the child is sitting in the second row
center seat position, move the child toward the
safety belt buckle. In either case, be sure that the
shoulder belt still is on the child's shoulder, so
that in a crash the child's upper body would have
the restraint that belts provide. If the child is so
small that the shoulder belt is still very close to the
child's face or neck, you might want to place the
child in a seat that has a lap belt, if your vehicle
has one.
1-32
CAUTION:
{
Never do this.
Here a child is sitting in a seat that has a
lap-shoulder belt, but the shoulder part is
behind the child. If the child wears the belt in
this way, in a crash the child might slide under
the belt. The belt's force would then be applied
right on the child's abdomen. That could cause
serious or fatal injuries.