IDoc Acknowledgement with Receiver Party --> Logical System?

Hello,

we have the following scenario:

IDoc --> PI --> AS2 (Party/Business Component).

Acknowledgements should be sent back to the IDoc sender. However there is the usual error that the sender party cannot be converted to an ALE logical system. I know that the adapter specific identifiers have to be set for business systems or business components, but how is this done on party level in B2B scenarios (Note: partner agreements uses a logical system).

Thank you for your advice!