My child (5) was on an ED and I was on a guardian. I checked with our school first and they said she could attend school on a DTV. Some schools will am only accept kids on an ED.

We just moved to Bangkok so were on the ED for less than 90 days (which is the original ED Visa). When we left without the re-entry permit, it automatically cancelled. We got approved in Taipei shortly after. Please note if you are an ED extension (beyond the initial 90 days of the visa) the school must cancel it before you leave.

I've read some people were able to get the DTV with an existing visa and some people rejected, so I guess it depends on the embassy.