You have a few options to avoid making an Mpeg from an Mpeg and the poor results that route will lead to:
1> Render the quarters to AVI first IF you are applying FX or otherwise altering the (assumed) DV footage, otherwise redering at that stage is of no real advantage.
2>Render the quarters to Mpeg2 and bulid your DVD so that they are linked or you provide a menu for the viewer to choose which quater they want to watch.
3>Render the quarters to Mpeg2 and combine them into one file with another program, such as Mpeg Video Wizard.
Gary