Pontiac 2009 Vibe Owner's Manual page 41

According to accident statistics,
children and infants are safer when
properly restrained in a child restraint
system or infant restraint system
secured in a rear seating position.
In a crash, children who are not
buckled up can strike other people
who are buckled up, or can be
thrown out of the vehicle. Older
children need to use safety belts
properly.
{
CAUTION
Never do this.
Never allow two children to wear
the same safety belt. The safety
belt can not properly spread the
impact forces. In a crash, the two
children can be crushed together
and seriously injured. A safety
belt must be used by only one
person at a time.
{
CAUTION
Never do this.
Never allow a child to wear the
safety belt with the shoulder belt
behind their back. A child can be
seriously injured by not wearing
the lap-shoulder belt properly. In a
crash, the child would not be
restrained by the shoulder belt.
(Continued)
Seats and Restraints
CAUTION (Continued)
The child could move too far
forward increasing the chance of
head and neck injury. The child
might also slide under the lap
belt. The belt force would then be
applied right on the abdomen.
That could cause serious or fatal
injuries. The shoulder belt should
go over the shoulder and across
the chest.
1-37