Answer:
I'm not an expert on California law, but as I read it, the Single Action rule only applies to a loan secured by a mortgage or deed of trust. If your loan is secured by a perfected security interest in 3 DDA accounts (and how you would perfect a security interest in a DDA account is a whole separate question), then you should definitely be able to recover funds from all three accounts if your loan defaults. But I would check with local legal counsel familiar with collection law in your state before proceeding, not just asking some people on the internet.