Hello Cinzia,
Regarding creating service confirmations we can create only one confirmation for one line item of SC. If there are N line items we have to create N confirmations. This is because activation of Service bundling switch in SRM and this switch is irreversible. This switch is a facility/convenience for SRM PO's replicated to ECC to view all service line items in ECC without bundling. This scenario happens for both Service and Limit items.
I hope service bundling switch in your SRM system 7 EHP1 is activated.
There is no other way to create service confirmations for all items at one go.
We do have this inconvenience and raised this concern with SAP and no reply.
Hope, this answers your question.
Best Regards,
Kalyan