Hi we've played the original Talisman (1st edition)for many years and now want to add expansions to play at Christmas (City, Blood Moon and Reaper). is there any reason why they wouldn't be compatible with the original game? Don't really want to shell out for the 4th Edition just to be able to use the expansions

The gameplay is the same, the new edition adds the system of Fate. But the most notable reason why it will not be compatible is that the new Adventure cards look different, you would definitely tell them apart inside the deck..