When linking models into Navisworks Manage, it is possible to read over 60+ formats. But it's recommended to use either original format such as rvt or IFC. When using IFC's require the design team to use user defined property set for easier finding different important parameters under a tab of BIM Coordinators choice.
In Navisworks it's called Append to link a file, while Merge imports the file(can't update the link).
When Appending files, Navisworks by default looks for NWF-files. On the bottom there is a drop-down, change to all files or specific format.