To premise this, I have always known of the limitations of copying from a project to a family and I try to inform my users of this but every once in a while I am faced with someone bashing their head against a wall. For those of you who don't know, if you try to copy detail components from the project into a detail component family you are faced with this:
I don't really know why we are not allowed to do this but it is unfortunately a limitation. The limitation is with detail components, not detail lines. What I want to express though is the disconnect with the documentation for Revit and what one can actually do. To begin, one can still load .RVG files into a family, but you cannot save to .RVG since Revit 2008. This is from the help files under the definitions:
And here are the instructions from Autodesk for saving groups and it states that one can save a group as a .RVT or .RFA:
So what is the problem with this? If you can save a group as a .RFA then you can copy to another family, right? Well the problem is that there is not actually the ability to save a group as a .RFA. When one follows the instructions (Revit Application Button - Save As - Library - Group (Or rightclick on group in Project Browser) one can only save a .RVT.
As a wrap up, I want to stress the need to think before you detail within the project. Try to determine if you want to detail using separate detail components or embed multiple detail components into one larger detail component, for example a parapet detail that will repeat multiple times. I know you are thinking, "Why doesn't he just use detail groups for the repeating details?" Well, that is for another post but basically you cannot put faith in the consistency of detail groups. Detail components will sometimes move, drop out of a detail group and you will face the dreaded ungroup or create new group dilemma. These group issues are the reason one of my users is about to throw her computer out the window. Now she has to waste an enormous amount of time just so that we can ensure that the details are consistent by redrawing complex details in a new detail component with no reference back to the model.
Not very BIM... am I missing something obvious?
Check out this information from Luke at http://whatrevitwants.blogspot.com/
Did not work for detail components but may give some individuals a work around for some cases.
A mystery commenter pointed out that if you actually ready the first line of the instructions, Who does that? :), then one would see that RFA saved group is only an ability if you are in the family.
By golly... mystery person was correct. Oversight on my part. Still, it does not resolve the issue that one needs to resolve a detail in the project, groups are buggy to the point that they cannot be trusted and then you cannot copy the detail components to a new detail component family. So one is stuck with unreliable details in the project or detailing without the project as a background.
Pick your evil