In some cases, it would be very useful to be able to add options to categorical markets after the fact. Take, for example, a market on the likely democratic nominee. As potential nominees enter and leave the race, it would be great to be able to add them.
This is possible in the conditional tokens contracts by creating a number of additional outcomes (up to 256 total) when the market is created, say 1, 2 and “other”. Where “other” is outcomes 3-256 merged. When a new outcome is added, we simply split one from “other”. So the market is now 1, 2, 3, and “other” (4-256).
Unfortunately, the oracle does not support this yet.