Hello,
partial decision (mix decision of approval/rejection items) for offline approval is not available in SRM standard.
If you want to have this functionality, you need custom developments.
One possible scenario could be:
1- manage decision link creation (FORM decision_links in report /SAPSRM/OFFLINEAPPROVALSEND), in order to create a third decision link with new text where approver will set (with a flag) his decision for each item after clicking onto this specific decision hyper-link and before sending decision mail,
2- manage e-mail data extraction (EMAIL_DATA_EXTRACT method from /SAPSRM/CL_OFFLINEAPP_INBOUND class) in order to get decision for each item,
3- manage decision for each item of the decision set instead of setting a whole decision for decision set of items (inside PROCESS_DECISION method from /SAPSRM/CL_OFFLINEAPPINBOUND class) using SET_ITEM_DECISION method from /SAPSRM/Cl_WF_ASV_FACADE_V20 class instead of SET_DECISION method as done by SAP standard.
It should work: you can check it.
Regards.
Laurent.