Firstly make sure that recommended settings are set.

Append all files from the necessary stakeholders.

Save a .nwf, which will be the project file.

Recommended to create a view for each level. Enable sectioning.

Select box

Select a level in the Selection Tree, and use "Fit Selection".

Change the x-/y- axis to fit entire model.

Right click in Saved Viewpoints and save the view.

Continue for the rest of the project.