You can use the lens flare on the original background, but you can't move it later. You can use the preview to place it as close as possible, but I believe the original request was for greater control over the placement.

Since you can't render a lens flare in an empty layer, I suggested using a black layer in screen mode. The masking step helps to avoid the edges that may appear if the flare effects go beyond the image border.

Another approach would be to:
- make a much larger canvas size
- new black layer, set to Screen mode, render lens flare
- canvas size bask to original dimensions
- move lens flare layer to exact position desired

To be fair, moving the flare too far away from the original location will make it the effect 'optically incorrect'.

I have my own silly way to do things... nothing crisp, but here it is:

Thanks for posting this. I just played with it in Paint Shop Pro 12. The result is identical.