This is one of our favorite organization tricks for homes that are multi level. Keep a small basket on the stairs for each child (or each room upstairs). This and other DIY organization ideas from this site!
Organize kid's toys by providing visual cues. Print photos of toys and place them in frames. Attach the frames to plastic bins to designate where blocks, action figures, and other small toys belong. Framed for Organization
Brilliant Ways to Organize Your Kids Stuff: Organize kid bedrooms, organize toys in the living room, and organize on the go! Each kids names on them for sports or swimming so their stuff is always together.