I have a corporation with multiple DBA's that I need to start filing CTRs on. The DBAs all operate under same TIN but have different names and addresses. I think I just need to check multiple persons box and fill out extras of PART 1 for the other DBAs.

thanks

Only if you have transactions for those DBA's. If there are 4 DBA's and only 2 have cash transactions and the aggregate is reportable, then only report the 2 DBA's that had the transactions and the main company in Part I.