Hello all!

As said in the title I have a recording of something that I would like to put together with he multicam feature; The problem is the main source is 1080i (1440x1080) and the other sources come from SD variations (720x576) I was wandering what is the best thing to do here, upscaling is really not my game plan so I was planing on just making a black screen around it to fit to 1080, does anyone have any better ideas?