Graco UNO2DUO Owner's Manual page 24

2. To attach seat, place seat on
mounts as shown until they lock
into place on both sides of the
stroller.
3. MAKE SURE seat mounts are
securely attached to the stroller
on both sides as shown.
4. CHECK that toddler seat is
securely attached to the stroller
by pulling up on toddler seat.
SNAP!
¡CRAC!