You will need

Jacket
3 - 6 months (16in Chest) 2 Balls
6 - 9 months (18in Chest) 3 Balls
12 - 18 months (20 - 22in Chest) 4 Balls
18 - 24 months (24in Chest) 4 Balls

Cardigan
3 - 6 months (16in Chest) 2 Balls
6 - 9 months (18in Chest) 2 Balls
12 - 18 months (20 - 22in Chest) 3 Balls
18 - 24 months (24in Chest) 4 Balls

Sweater
3 - 6 months (16in Chest) 2 Balls
6 - 9 months (18in Chest) 3 Balls
12 - 18 months (20 - 22in Chest) 3 Balls
18 - 24 months (24in Chest) 4 Balls

8mm Needles
2 Buttons for Jacket
2 (2 : 3 : 3) Buttons for Cardigan
2 Buttons for Sweater