Hello Jim,
Many thanks for your reply, Tulwar hilted kukri were certainley in use in Nepal before the Anglo Nepali war of 1814-1816, captured versions in 1806 came from Palpa in the Palpa war Nepal, pic below;
So I would say they were almost certainley in use in the 18th century in Nepal as well.
Tulwar had long been in use in Nepal before 18th century, so I would think it was more than likely that it was a natural Nepalese development, and these styles were quite common in Nepalese households at one time;
Cheers Simon