Chevrolet 2009 Suburban Owner's Manual page 80

If more than one child restraint needs to be installed in
the rear seat, be sure to read Where to Put the
Restraint on page 1-63.
The vehicle's lap-shoulder belts for the first and second
row seating positions are equipped with free-falling
latch plates. If the vehicle has a third row, the
lap-shoulder belts have either free-falling or cinching
latch plates.
Use the following pictures to determine the latch plate
style:
Free-Falling Latch Plate
1-74
Cinching Latch Plate
1. Put the child restraint on the seat.
2. Pick up the latch plate, and run the lap and shoulder
portions of the vehicle's safety belt through or
around the restraint. The child restraint instructions
will show you how.