SC approver's per item wise

Hi Experts,

How to derive the SC approver's per item wise?

Example: Lets say suppose SC has 5 items and the approver logic determination based on Product category..(Product category approvers maintained in custom table). Assume that product category 3 & 4 does not have approver's maintained in custom table.So, in that case how to derive the approver per item wise..

Item 1 = Product category1

Item 2 = Product category2

Item 3 = Product category3

Item 4 = Product category4

Item 5 = Product category5

How to write the code for the above example in the BADI of /SAPSRM/BD_WF_RESP_RESOLVER methods
/SAPSRM/IF_EX_WF_RESP_RESOLVER~GET_APPROVERS_BY_AREA_GUID
/SAPSRM/IF_EX_WF_RESP_RESOLVER~GET_AREA_TO_ITEM_MAP

or else is there any other way?

Thanks,

Krishna.