Overlay track as a background ? (4:3 to 16:9 adding border)

[su_A_ve]

I have some footage done in 4:3 and using most of the screen (top to bottom) so it's not possible to convert to 16:9 by cropping top/bottom.

So for these projects, I looked at doing them in 16:9, but adding a background (video and/or still), so it'll be better than the black bars.

It works, but it's teddious. How I've done it so far was:

Create the whole project in 4:3.
Render the avi
Create a new project in 16:9, adding the background and still to the main track, and adding the 4:3 avi to the overlay track
Render again

Now, I just found out that I could skip the 4:3 render step and instead add the 4:3 project to the overlay track so it'll be easier...

Is there an easier way ? Ie have the main track be on top of the overlay track and just adding the background to the overlay track ? When I do it, the overlay track goes on top regardless. Or, a video filter that adds the background (though I'd rather deal with overlay track as I would be able to do not just a still but a movie too).

BTW, the final product is then burned in 16:9 Pan and Scan. So if's viewed in a 4:3 TV, it's full screen. If it's seen in a 16:9 screen it'll be widescreen (with the border). The border starts as a movie clip then transitions to a still image, then later transitions to a clip at the end...

TIA..

[Black Lab]

The background color can be changed from black to any color you want - File>Preferences>General tab. Would that solve your problem?