I have talked with an exceptional Xbox Support agent over chat about this problem already, and they advised me to post this on the forums as well. So that is what I am doing :)
Basically my problem is with Fallout 3's five DLC packs. I bought the Game of the Year edition of Fallout 3 a year or so ago which came with the main game on one disk, and the five DLC packs - Operation: Anchorage, The Pitt, Broken Steel, Point Lookout, and Mothership Zeta - on a second disk for installation directly to your Xbox 360's hard drive. The reason it does not recognize I own the DLC on my Xbox One is because I did not buy them from the Xbox 360 Marketplace, but installed it off the second disk. So as my support rep said, the licenses for the DLC are not found on my account because there was no transaction made. And the licenses for my DLC are also on the second disk so it does now show up (the second disk is not recognized on the Xbox One because it does not contain a game, only the DLCs, therefore telling me it is a disk that is not currently compatible with Xbox One backwards compatibility). The wonderful support rep told me that the disks which contain the DLC are not yet compatible, so pretty much I cannot do anything about it yet. So my Fallout 3 is unplayable currently without the DLCs because my save file in the Cloud contains the DLC packs, so I do not wish to corrupt it by loading it until I have the five DLC packs on my Xbox One.
The Xbox Support Rep said he was documenting my case and sending it to the higher ups/engineers for them to look at and investigate to see if they could possibly fix this issue by adding a feature that would read the Xbox 360 disks which only contain the DLC. Which then would allow myself (and others) the ability to download/install the Xbox 360 DLC they own on their Xbox One for the backwards compatibility feature of Xbox One.
Personally this would really help me out (and I assume others) not just now, but in the future. As more Xbox 360 games become available for backwards compatibility, the more this issue could arise with people. Because there are many games for the Xbox 360 that were re-released in Game of the Year editions, or special editions, or complete editions which contained all the extra content and DLC on a separate disk (or same disk as the main game sometimes). So all that DLC would not show up on the Xbox One as is right now because there were no digital transactions to show that someone owns DLC to a certain game. I hope this can be fixed soon. Otherwise, have a great day any and all! :)