Can I apply for my family’s DTV under my account or do they need separate applications?

I have no experience or read feedbackabout DTV applications from others who did.

BUT for other types of visa, dependents can apply at the same time and use a screen shot from the main visa application.

BUT lots of people advice wait until the main DTV is issued before you start the dependents application, no idea why the information changed based on another type of visa.

Contact the Embassy you are going to use and ask them if you can apply all together or have to wait until a visa is issued before applying for the rest of the family.

No issue using your evisa login to file applications for your family members.

Of course you have to wait until yours is approved, how are you going to refer dependants to the main DTV holder without an approved visa number already?

You can only apply for their dependant DTVs once your DTV is approved. You can pre-fill the applications as much as possible in the meantime though.