Fisher-Price GROW-WITH-ME 79711 - Manual (Page 64)

NEVER put anything on your vehicle seat (such as a cushion)
to raise the car seat. This will create too much slack in the
vehicle belt system. In a sudden stop or crash, a loose vehicle
belt system will not be able to properly restrain your child.
NEVER use the car seat after it is involved in a crash. A crash
can cause damage to the booster car seat that you cannot see.
NEVER allow the vehicle shoulder belt to be moved off of
your child’s shoulder. It is critical that your child not move the
vehicle shoulder belt out of position after you have adjusted it.
WARNING
Booster Car Seat Mode 4 30-80 lbs.