To make alternatives to a wall you have to move the wall from the mainmodel to all dessign options in a design option set. Then make your modifications in each option. The warning you get, must have somthing to do with hosted element on the wall you are trying to copy.

Right, but I can't move my wall to a DO because of the 82 warnings. I don't want to move half of my construction set to a design option. It's an exterior wall that has stairs, curtain walls, lighting, ceilings, roofs, stacked walls, etc all associated with it.

If I would have started from the beginning with this wall in a DO I would be ok, but unfortunately the value engineering only occurs after a bulk of the work is complete.

We had to look at taking a structural bay out of the design and was running into the same problems and error messages you are seeing. I copied the entire model to a DO and was expecting the worse but it worked and the file size only increased by about 20%.

I had to do this once and I did what the OP suggested as the easiest...I just saved off multiple copies of the project and when it was all said and done I deleted those copies I no longer needed. Sometimes, when time is of the essence you have to do what is easiest. Just my .02 worth.

The problem with multiple copies is you can only keep working on one

If DO are a no go, what about grouping the wall and associated elements for that elevation and saving the group out as a new .rvt. You could then create multiple rvts for each study or possibly get DO working in that file. Once an option is selected link and bind. Not ideal but could work.

Design Options are EXACTLY what you want. You just cant add "the wall" without all the "stuff" that is dependant on the wall. It makes perfect sense.

Heck, we will have 4 or 5 sets of options in a file at any point in time. If you take some time to be patient and learn how they work, they are one of the best tools in the program. if you get mad because you are guessing and not guessing correctly, then yeah... You will hate them.

And dont buy in to any of he bad threads out there on how Design Options only work early, or are only for certain things. ive sued them on micro stuff (furniture layout), macro stuff (which portion of the building to demolish and add on to), early in concept design, or entirely after CD's have occurred. The rules dont change. They still work great, as long as you know how they work.

Lastly, file size doesnt mean squat, and a 70MB file is tiny. I wouldnt sweat it at all. But i certainly wouldnt copy the file, i wouldnt save out groups, and i CERTAINLY wouldnt go out to CAD... When there is a tool made JUST for this cause. Just experiment with it and learn what to do, to make it work. Its TELLING you what the problem is. (Select the wall AND THE WINDOWS and DOORS!)

I'd go with Design Options for all the reasons Aaron just mentioned above. Do you want to copy all elements attached?
Try assigning the wall to DO. You'll get the error box. Expand the error box, and export it. Then open in text editor, delete all but the element ID's and hit Cntrl-C. Now in Revit go to Manage > Select by ID, Paste all Element ID's in the textbox and hit OK. After this, use the Cntrl-Click to add the wall to your selection and add those to Design Options. If done correctly, you should now be able to move all to the DO's.

Remember though that you can only add to a DO once. So first create all possible Options (plus one to be sure), then assign...

Interesting, wasn't aware of that process