New field addition in "Selective replication"

Hello,

I need to add a new field to the "Selective replication" of a table i.e we have 12 fields out of 40 selected for selective replication. I need to add one more field to the list. My question is, how would i initialize data for the new field i.e all the 12 fields have data already coming from ECC and i need to populate the new field as well with data for all the existing rows. The new field added is a standard SAP field. Can you please help me with the same?

Regards,

Prem