Use Origin to Origin, if you don't NEED Shared Coordinates for other reasons.

Hi Cliff, thanks for your suggestion, but I'm not sure I understand... I can link the model origin to origin (and then move the link to align property line to property line), but that doesn't seem to help when I paste an element between the models, i.e. if I open up the site model and then paste an element in, it's still not pasting it in the same position relative to the property lines.

If you only have one building, then link your civil cad plan into your building model and create a revit topo from that in lieu of a separate 'site model'.

Thanks for the suggestion Charles... that's not quite the issue.

I guess I wasn't clear... I'm trying to understand whether it's possible to adjust the internal coordinate system so that a specific spot in one model is the exact spot in another model... without actually "moving" any geometry. I want to be able to copy and paste between the models and have elements appear in the same spot in each model.

I'm not really looking for "work-arounds"... it's easy enough to use the property lines in each model as a reference point, but then each time I paste something between the models, I have to manually move it per the reference point. Ideally I'd like to avoid having to manually move the elements after I paste them.

Paste Aligned is only aware of the Project Coordinate System. There is no way to tell it otherwise. The only way something will paste to exactly to the same location between files is if they are linked Origin to Origin. If Center to Center works, it was a fluke because center (file extent) to center (file extent) varies from moment to moment...unless nothing exceeds the property boundary so the extents is the same.

Thanks Steve for that explanation - but I kind of feel I'm still missing something about everyone's suggestions, or I just really messed up my initial post. So maybe I can start again that explains the issue at its most basic...

Forget about the links, that seems like a red herring - so no links in this example... just two completely separate project files, each with a site plan view.

In Project A, I draw a 50' x 100' lot in the white space on the screen.

In Project B, I draw a 50' x 100' lot in the white space on the screen.

The starting points were completely random, so they are not in identical positions in the coordinate system.

I draw a wall element in Project A right along one of the property lines.

I want the wall to be positioned in the exact same place along the the property line in Project B. So I copy (from Project A) and paste to current view in Project B, but the wall is not positioned in the same place relative to the property line.

Is there a way to change the coordinate system in one (or both files as necessary) so that when I paste from Project A to Project B, the elements will paste in the same positioning relative to the property lines.

It doesn't matter the reason in this example, I cannot use the "move" tool to move the modeled elements in Project B so they are in the same position as Project A.

If there is a solution, I know it might seem overwhelming to provide step by step or a full explanation, but if you or anyone can definitely say, yeah, you can do that, you just need to keep working with the coordinates tools, then at least I know I'm not wasting my time trying to get this to work. And if anyone can provide a further point in direction, like, you need to work with the acquire/publish coordinates tools or something like that, then I'll keep trying that... again, I just don't even know if what I'm asking is possible?

Thanks for your patience with me!

Short answer, no. Nothing will change Paste Aligned assumptions. It’s based on file origin only. Include something (model line) that makes it easier to move the elements to the correct location afterward.

Try working in a plan view set to true north in project A. Then link in project B and align two known points (preferably grids) then save the new position back to Project B.

Thanks Steve! Now I can stop spending time trying to figure out the impossible.

I'm not sure what you mean by "save the new position back", but I tried this as in "Publish Coordinates" to Project B, and it doesn't work. As Steve indicated, apparently there is a "file origin" that can't be changed that past aligned is based on.