Without actual editing -- no. You might be able to pull of a script to do it in realtime but it is certainly not going to happen in powerdvd, media player classic or whatever DVD program you are using. It might have an option to stretch the thing back to 4:3 but it will distort it in some way.
CSI style. Actually yes in some cases (most of which you are not especially likely to encounter) but not the horizontal one I saw in whatever show it was.
Back on topic so to speak.
If I understand it
You have a new video disc, in this case of a wrestling show, which has full glorious HD in 16:9 or something similar. It comes with a SD/DVD option but the cowboys that made it letter boxed it so you are missing the edges of the picture. Alternatively the HD source is the full original source as the camera got and it the SD stuff was an afterthought made badly.
Either way your HD source has the full picture in the style you want to watch where the SD source is effectively cropped or otherwise hosed up. You ask can you then take the HD source and use it to patch in the missing sections? Assuming they are both decrypted then absolutely.
Problems -- simple letterbox amounts to resizing and cropping and stitching back together which is annoying but quite doable inside 20 minutes (plus encoding time) if you know what you are doing. There is a more dynamic letterbox (which sadly did get a nice automated filter that anybody that can click a few times could try out) that tries to identify action and either letterbox accordingly or in the even more annoying cases zoom in and out according.
Other potential problems are the usual video ones where frames might not be synced, have an odd pulldown method or something similar. I am assuming it is the same video where it matters and one was not recut or something.
First solution -- give up, get the HD source ripped, drop the resolution and encode it as a DVD. I must admit I have not paid attention to BD ripping of late so I do not know what free methods are out there are any good (
http://www.dvdfab.com/hd-decrypter.htm and
http://www.slysoft.com/en/anydvdhd.html would be what I would probably just say screw it and get ). The drop the resolution part is easy (if using something like
https://sites.google.com/site/favcfavc/ ,
http://www.dvdflick.net/ or some other good DVD making software it will probably do it for you) and the encoding is easy as well as long as you are not especially attached to the menus (you can still have several shows/clips on would be DVD though).
Second solution-- give up, get the HD source ripped, encode it as a DVD stream and remake the old DVD. An utter arseache if you ask me but still doable. Here you would have to learn to edit existing DVDs which is not necessarily the easiest for what you might want to do (pcgedit, vobedit, vob blanker and ifoedit being my first ports of call/assembly of my toolbox for the task).
Third solution -- the restoration project. This is the decode, resize/match clips, crop and stitch. Here someone gets to teach you proper video editing unless you get very lucky and can just overlay the SD video at the appropriate point of the former HD stream.
I do not encourage the third solution where there is an easier way.
