So in other (not already specified) words, you have ONE 7.5GB file, which you want to burn on two SL-DVDs?
Have you tried this?
Disc Spanning
If you are creating a Mac Only or Mac & PC data disc, you can record large files and folders, even if they exceed the recording capacity of a single disc. If you do, Toast advises you of approximately how many blank discs are needed, and automatically spans the data across them.
The completed group of discs is called a disc set. Each disc in the set contains an index of the contents and location for every file and folder in the set.
To span discs:
1. Prepare your disc as you normally would.
See Making a Mac Only Disc on page 46 or Making a Mac & PC Disc on page 52.
As you add data to the Content Area, the left side of the Toast window displays information about the number of discs you will need for recording. Click the disc capacity pop-up menu next to the Space indicator to adjust the information for CD, DVD, or Blu-ray disc media.
2. Record your disc. Toast will prompt you to insert each blank disc while recording.
