Unble to Merge Multi PO to create Confirmation & Invoice in SRM7.0

Hi Experts ,

We are configuring SRM7.0 with ECC6 ( Ehp4) having Classic Scenario

While creating the Confirmation or Invoice , when we search the PO ( Find button) and list of PO appears , then we unable to select/ merge multiple PO...by using shift key ..... these POs have exactly same data except Material code and same POs, we can merge in the ECC in MIGO transaction code.

Can anyone suggest, wheter it is possible to merge multi PO to craete Confirmation & Invoice in SRM7.0 ?

Thanks

NAP