Seat assembly for a passenger conveyance device, especially of a wheelchair or of a scooter, with a seat frame for carrying a seat cushion, wherein the seat cushion comprises a central cushion member, placed on at least one central seat member, between two lateral cushion members (3, 7), each placed on a lateral seat member (30, 300; 70, 700), with • at least one of the two lateral seat members (30, 300; 70, 700) being removable from the seat assembly together with the respective lateral cushion member (3, 7) placed thereon, • the at least one removable lateral seat member (30, 300; 70, 700) being attached to the at least one central seat member via a latch, plug, frictional and/or form connection, which connection is detachable and lockable, and • the at least one removable lateral seat member (30, 300; 70, 700) being pivotable with respect to the at least one central seat member via a pivot connection, • wherein a first part (704, 706) of each latch, plug, frictional and/or form connection, the pivot connection and/or the plug connection is provided by a lateral outer portion of the central seat member, and a mating second part (711, 713) of each latch, plug, frictional and/or form connection, the pivot connection and/or the plug connection is provided by the at least one removable lateral seat member (300, 700), and • the at least one removable lateral seat member (30, 300; 70, 700) being provided with • at least one profile for the attachment of the respective lateral cushion member (3, 7), • a through hole for a pivot pin to provide the pivot connection, and/or • a slot for a hook to provide a latch connection. • at least one of the two lateral seat members (30, 300; 70, 700) being removable from the seat assembly together with the respective lateral cushion member (3, 7) placed thereon, • the at least one removable lateral seat member (30, 300; 70, 700) being attached to the at least one central seat member via a latch, plug, frictional and/or form connection, which connection is detachable and lockable, and • the at least one removable lateral seat member (30, 300; 70, 700) being pivotable with respect to the at least one central seat member via a pivot connection, • wherein a first part (704, 706) of each latch, plug, frictional and/or form connection, the pivot connection and/or the plug connection is provided by a lateral outer portion of the central seat member, and a mating second part (711, 713) of each latch, plug, frictional and/or form connection, the pivot connection and/or the plug connection is provided by the at least one removable lateral seat member (300, 700), and • the at least one removable lateral seat member (30, 300; 70, 700) being provided with • at least one profile for the attachment of the respective lateral cushion member (3, 7), • a through hole for a pivot pin to provide the pivot connection, and/or • a slot for a hook to provide a latch connection. • wherein a first part (704, 706) of each latch, plug, frictional and/or form connection, the pivot connection and/or the plug connection is provided by a lateral outer portion of the central seat member, and a mating second part (711, 713) of each latch, plug, frictional and/or form connection, the pivot connection and/or the plug connection is provided by the at least one removable lateral seat member (300, 700), and • the at least one removable lateral seat member (30, 300; 70, 700) being provided with • at least one profile for the attachment of the respective lateral cushion member (3, 7), • a through hole for a pivot pin to provide the pivot connection, and/or • a slot for a hook to provide a latch connection. • at least one profile for the attachment of the respective lateral cushion member (3, 7), • a through hole for a pivot pin to provide the pivot connection, and/or • a slot for a hook to provide a latch connection.