Player #1 starts from the safe zone. She can join the centeral zone after the first pass. After the ball crocess a line and goes to one of the end zones (Z1 or Z3), middle zone (Z2) players can enter that zone. The opposite side zone playes can enter the middle zone. So basically Z1 players can play in Z1 & Z2. Z2 players can play in all 3 zones.  When the ball goes out or a goal is scored, the red team starts on one zone. Alternate starting zones.