This is our case: 

We work with an engineering service provider that uses CATIA V5 and is also connected to the 3DX platform. 
We work with CATIA 3DX.

We would like to integrate their data into our product structure and preferably directly into our CATProducts. It would be perfect if we could work together as a team without them also having to use CATIA 3DX. It would also be fine if we could enter their smart data ourselves (but preferably also see the history).

At the moment, we have tried this by giving a person there licenses and access to our system in the same way as we did to our employees. This person exports data (from 3DX to V5) and imports data (from V5 to 3DX). With the latter, a problem has already occurred a few times because the data was created in 3DX, edited in V5 and then uploaded back to 3DX. According to the error message, this situation is not permitted:

Is there any conceivable workaround how we can realize this?

Thank you very much for your help!