Undoing hot water tanks in parallel

[taffyinhighlands]

I've got a DHW system with 2 storage tanks run in parallel - everything is well set up for the 2 tank operation, but other than completely removing one tank, and draining it to avoid legionella risk, is there a way I can keep both hooked up but only run the single tank (system was installed for 14 ppl, but usually only 5 there now) for most of the time, bringing back online with other one only when its needed?

thanks in advance