I had just completed Take It Back and found out not knowing how Fallout 3 ended that either the Lone Wanderer or Lyons dies starting the Purifier but either way the game just ends. I did my best not to be spoiled considering I am playing Fallout later in its life. Well apparently I did a pretty good job because I did not expect this. The only saves of this play through that I have is me about halfway through the Take It Back quest. My question is if I download Broken Steel will it be applied to this play though even though I have already started Take It Back. I have dumped a lot of hours into this single game play and did a lot of quest before even going deep into the main quest so I was hoping to extend my play more. I barely have had time to play with the Power Armors, or Plasma weapons outside A3-21s I got through The Replicated Man. Thanks for any help with this matter.

If you already started Take it Back you should be fine. Any official DLC will not affect your playthrough be in Operation Anchorage or Broken Steel. In broken Steel's case, after beating the game you will continue two weeks later, you will know what I am talking about.