Functional Group more than one species parameters

[Samroz Majeed Baloch]

some papers there are mentioned they include more than one species in a functional group like

1. Prawns 

Penaeus monodon

P. indicus

P. semisulcatus, 

Metapenaeus dobsoni 

M. Monocerous Macrobrachiumsp.

                                          

2.    Perches

Lates calcarifer 

Rhabdosarguss arba

 Crenidens crenidens

 Datnioides polota

How can we take these species' Q/B, P/B, diet matrix, and biomass?

is it like we need to sum the Q/B of all the groups and divide by the number of groups?

Thanks