Hoov,
Perhaps you should work for CRA, lol. They couldn't answer that question. The CRA agent did mention something about an election, but then she got sidetracked.
Although Boatboy's post makes much more sense, CRA has their own views of common sense, I guess. So when/if establishing the ACB for the FWR shares into NOT shares, you need to look at your own individual situation and do some calculations. Just as BB and Hoov have suggested.
Personally, I have a spreadsheet for each stock I have invested in, with the date of purchase/sale, price, commissions, total, capital gain/loss and the 50% of that gain/loss. And prior to every sell, I work out the ACB and calculate my gain/loss right then & there. Saves time at the end of the year, especially if you have a lot of trades.
strato