Thanks Charlotte, I believe that does give the answer I was looking for.
So, as the existing company will remain as a listed company, my open positions will remain as they are, and as the terms of the demerger are that each shareholder will be granted 1 share of the new separate company for each of their shares in the original company, I assume that when the demerger is affected a new position for the equivalent number of shares will automatically be opened for me in the new company and i would then have open positions in both companies