You can tag with multiple canons (or any other category) by holding down CTRL and clicking them.

Alternate ending/sequel... I had these separate initially, until someone convinced me that there wasn't a material difference between tacking on a different/net ending and writing a sequel. In our minds, the alternate ending didn't contain most of canon. In my mind, Kissing the Frog is an alternate ending--Christine comes back. That's it.

AU would definitely be the "spies" idea, or that one where they're in a POW camp in Vietnam or something (seriously).

I'm not sure where Persia would fit.

I'm thinking about all of this, thank you.