Can i join 2 fields in Kibana

I have two types of Tables in one index
Table A- > Internal IP Address, External IP Address, User Name, Connection Reason
Table B -> External IP Address, User Name, Session Transfer, Duration

I want to create "match the field "External IP Address" from Table A = Table B in order to get Internal IP Address in to Table B

You can't do this in ES either, you need to enrich the document at index time.

Can you please elaborate how this can be done during the index time ? We could do this in Hive or even Tableau, but how can we achieve this through ELK stack ?

Use Logstash and the translate filter perhaps?