Several brokerage accounts. Can I declare only some of them on kakutei shinkoku?

If I were to hold 2 different accounts, 1 being tokutei kouza gensen choushu ari, another one being tokutei kouza gensen choshu nashi or ippan kouza, and have no other income, can I choose to declare only the tokutei kouza gensen choshu nashi or ippan kouza for kakutei shinkoku purpose? Or would I have to declare both?

And is there any advantage for choosing ippan kouza over tokutei kouza gensen choshu nashi, since the taxation treatment is the same, but for the latter your brokerage would have prepared the calculation for you? Thanks in advance!