They join four previously announced team members: Valerie Adams (shot put), Mary Davies (marathon), Quentin Rew (50km walk) and Nick Willis (1500m).
Adams begins her Diamond League campaign this weekend at the Prefontaine Classic in Eugene, Oregon. Davies has recently run a 32:08 10km personal best in Ottawa, Canada and continues her preparations in Houston, Texas.
Rew is training from his English base and Willis has cut short his early season racing following a minor injury.