I can feel your frustration. It sounds like you are creating your own Graphics material to show on a DVD. You mentioned no source footage. I’m a little confused there. What are you actually going to show on the DVD?
If you create graphics, make the size 1920 x 1080 for HD or widescreen format.
Your source footage needs to be widescreen format 16:9. It doesn’t have to be HD. HD & SD doesn’t matter as long as the footage shot or graphics created are made the correct size.
Otherwise your 4:3 standard will not fill the screen.