According to the NPC Rules of Procedure, the heads and deputy heads of the various NPC delegations are elected at the plenary sessions of their delegations. To be eligible for election they must be deputies to the National People's Congress.
The head of a delegation is responsible for convening and chairing plenary sessions of the delegation assisted by the deputy head. The head would also usually be a member of the Presidium and report back to the delegation on the work of the Presidium. He will also represent the views of his own delegation both at meetings of the Presidium and at plenary sessions of the NPC.
NPC Rules of Procedure provide for delegations to be sub-divided into groups, with each electing its own convenor. This is to help give the deputies every opportunity to air their views. A typical group might be composed of say 10 to 30 deputies and correspond with a prefecture within a province. Chaired by its convenor, the forum of the group meeting facilitates discussion by members of the delegation on the various bills and proposals. However a delegation with only a small number of deputies would not be sub-divided in this way.