AP Charge allocation in Oracle 11i , How is this driven ?

 I am looking for a setup/config option which drives the Allocations in Oracle AP and distribute the allocated amount across items? 

In my instance ( 11.5.10) , what I found was if one invoice having 200 line types as ITEM and one Miscellaneous and the Miscellaneous item amount is Zero , it is creating 200 zero $ lines in AP_CHRG_ALLOCATIONS_ALL table. Since these are not required we are looking for a purge script which can purge the zero $ amounts in this AP_CHRG_ALLOCATIONS_ALL table without any application impacts.

Also what is driving to proportionate distribution of charge across all the item line types? May be we need to reconfig the application ( If Possible)   so that 0 $ amount in Misc line type should not be distributed as it does not add any value other than creating more n more lines in the CHRG_ALLOCATION table.