Nine-Character Group Scene in Living Room Background

Please stitch the file I just attached into a 3x3 grid to generate a horizontal long file. After merging, adjust the long side to 1400 pixels and maintain the aspect ratio. Set quality to 100% (highest quality) and output in JPG format.

Using the background from the first attachment image (living room), place the nine characters from the second attachment image (character sheet) in the living room, letting them spend leisure time, such as sitting on the sofa, looking at photos on the wall, picking up books, sitting on the floor chatting, etc.