How many GR/IR accounts are to be defined

hi,

i have defined 5 inventory gl accounts one for each type of material group. As such do i have to specify all the 5 gl accounts in the BSX transaction key of OBYC screen or only one? Under the same example how many GR/IR accounts do i have to specify for WRX transaction key?

If the answer is i have to specify only one inventory account and one GR/IR account, how can i handle all the 5 different material groups using this single inventory and GR/IR account?