Is there any way to convert NWC2 files so they can be used in NWC1?
NWC2 is such a pain, when you make a file with a particular version it won't open in an older version so when you send it by email it can't be used by others. It can be viewed by NWC2 Viewer, but not adjusted i.e pan or volume,etc. and cannot be started except at the begining.
I must make sure I don't use it in future.
There is no way.
I'm sure NWC Online will respond soon, but I would guess the answer is no. I think the code is too different to allow for an easy conversion, just as a direct conversion of NWC1 to, say, Finale or Sibelius would be more trouble than to export as MIDI and then import as MIDI into the receiving software.
If you use MIDI for the conversion, temporarily put a Performance Style ... of Tenuto or Legato at the beginning of each staff. It will make the import much cleaner.
Currently, there is not a NWC2 to NWC1 conversion tool.