I think you are missing the data source name here and it is something like belownms:extAccount:FDAxxx

I am making a guess here. did you check the typology rules and also check the "Keep duplicate records (same identifier)"check here and you can do the opposite of what was achieved.Include duplicate email ids in a delivery

Visakha​How are referring the option variable in the template? can you post the syntax? check if this thread helps.Can we use Option Variable in personalisation block

shansjtrex​Right now we do not have this in ACS and you can expect it soon in future releases.