Hi,
Transaction in EWM is 'BP' and ID type is CRM002 ( please note that all BPs are maintained with this transaction only Eg : Vendor with ID type CRM004).
Normally we move the vendors and customers through CIF functionality from ECC system through integration model.
Table : /SCMB/D_BPTMGEN.
field : ' BU_PARTNER'.
Other tables also there to get the delivery relevant data...
C K Reddy