Fiat Multipla Owner's Handbook Manual page 115

Centre seat belt
The belt has a double buckle. Slowly unwind the belt from its reel (A),
take the tongue (D) and insert it in slot (E), then place tongue (B) in slot
(C); make sure both buckles lock properly.
When there is no-one in the centre seat fold both belt sections and place
the buckles in the receptacle (A), inside the locking slots.
When refitting the seats take care not to reverse their positions: the
centre seat is easily distinguished by the table on the seat back.
WARNING
Remember that in the event of a violent collision, back seat passengers not
wearing seat belts also represent a serious danger for the front seat
passengers.
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