[quote=Kynapon]
I don't want to. It's a daunting list that will haunt me at night.
[/quote]

... Just wait until you see 'em in action!

You can have as many characters as you think you can handle. As for introducing her, you can simply insert her in a scene of your choosing, or if you're up to it, you can narrate her arrival on the island, and give a few reasons why she wasn't in the current events until now. Or you can do both.