It’s been my experience that as soon as two files have different rotation values in the project basepoint you will get the warning of different Coordinate sytems. Not True! As soon as you change any value in the project base point it goes wrong. But why does it sometimes go right?
Start a new file change the project basepoint and save the file under a name, let’s call it Project A.
Next you change the project-base-point again save that file under a another name, Project B.
If you link Project B into project A by shared coordinates it will place project B exactly where it should land.
In fact I have been using a copy of the same file and changing any value of the project basepoint, or survey point, unclipping it, moving it and so on and I do not get this screen when I link by shared coordinates. And more surprisingly it ends up where it should.
I have tested this both in Revit 2014 and 2015. No difference I’ll try to show this now in screenshots
Project A: just a floor no change to either survey or Project base point
Project A saved as Project B, but I changed the project base point N/S E/W values.
Project A saved as Project C, but I changed the project base point N/S E/W values and rotation.
Next I link Project B into Project A by shared coordinates and it lands exactly where it should. Next I link Project C into Project A by shared coordinates and it lands exactly where it should.
Now I will create a new project and setup the project base point exactly like project B but I will model a floor that should end up below Project B.
When you link Project D into Project B by shared coordinates you will get this.
Before I never had this problem because I always setup the project base point manually and I link the revit files origin to origin.
My conclusion is that something else controls the ability to use shared coordinates and that the values of the project base point or the survey point do not matter.
You would almost suggest you create one simple file at the start of the project and share this file to all companies who are going to work on the project. From a revit point of view that might work but from an organization point of view it’s quiet unlikely that that is going to work. What will work is if you all model relative to the revit origin and you link your files origin to origin! Once the files are in you can use the publish and acquire coordinates function.