Hi
From CRM to ECC BP Replication
In CRM txn : R3AC1
Object Name BUPA_MAIN Business Partner
Filter you can used
BUT000 BU_GROUP Business Partner Grouping = (Mention as per your requirement)
Grouping also represent number range you can also use number range filters
BUT000 PARTNER Business Partner ID BT = low to High
Regards,
Vaibhav Shah