This functionality has been added beginning with the 2.5.919 version. You will need to upgrade to this version or later to utilize this feature.
The PPM Affinity settings configured on the Managed System with the Discovery Profile will dictate which appliance processes the Account Discovery scan.
To have a DPA process the Account Discovery, ensure that the PPM Affinity is configured to prefer the DPA in question.
DPAs will not be used for account discovery in cases where SSH Tunneling is used or on platforms where a specific port is not allowed to be set - such as Windows type systems.