After much discussion, product support and testing different methods I have now found a fix to the problem right out of the blue.
The only problem is that in order to do this the user may be required to create a custom vb tool based on the OTB pipenetwork to excel function that I have previously used to import windes information.
The current issue is that only some information is extracted from civil3d pipe networks, custom added contexts do not get passed through the nwc export utitlity. I can't believe it but the answer was right under my nose all along.
The process is to tweak the exportpipenetwork to vba tool which ships with civil3d to search and extract all the required data. Obvously this is not an easy solution for most users but possibly a nessesary part. You may get some information from copying the Network vista.
You need to export this information to excel then create a datalink in Navisworks to target the Entity Handle then add the custom entries you need added. The missing information will then be added by matching handle. In order to bind the information into Navisworks you simply publish the data to an nwd file.
Process as link: Navisworks Datalink process.
Mike