There are described an apparatus (10) and a method for forming an assembly (A) comprising an organized group of smoking articles (11), an accessory element (12) and a reinforcement element (13), wherein the apparatus (10) comprises a forming conveyor (15) provided with a plurality of forming pockets (24), each configured to receive the assembly (A), a member (14) to feed the accessory element (12) and the reinforcement element (13), which is configured to feed them inside the pockets (24) according to a configuration whereby the accessory element (12) and the reinforcement element (13) are partly overlapping each other, and a thrust member (32) configured to introduce the organized group of smoking articles (11) inside the pocket (24).