Space Engine has good visuals and some features that UBox 3 won't have and/or features that will never be implemented. The same thing applies to Space Engine. If we could export/import SE files to UBox 3 or UBox 3 files to SE, that would be awesome! Just think about the possibilities!
SE's visuals is far more advance than what UBox 2 or 3 have or would have, also you can land on the celestial bodies like you we're living there which is quite better than the landing feature of UBox 3, on the other hand, Ubox can simulate gravity better and allows as to do a lot of interaction than SE.
So how would the partnership works? Both team will do their project on their own, instead they can discuss features that would make their projects better like the ability to export and import files from SE to UBox or UBox to SE or even UBox to SE to 3DS/Blender3D/Unity3D/ETC! By having such features, researchers and game developers can easily use those assets in many ways whether for personal use, public education, commercial works and more!
Let's discuss about it deeper shall we?