Or become bisexual. If anyone posted a procedural comment on how to become bisexual, I would upvote it immediately =)

Beware that if you manage to become bisexual somehow, this can significantly damage a man's prospects with many women. For a huge percentage of women, bisexual men are not as attractive (manly) as strictly heterosexual men.

Darn you, cliffhangers!

I want to know what effect Elspeth's other self will have on being Chelsea'd. If her other self can somehow propagate her love for her mother back to her, then that would take out a major chunk of the damage Chelsea can do to her. (Who else does Elspeth have a relationship with that Chelsea can nuke? Several people, Edward and the Denalis mostly; however, they aren't nearly as close to Elspeth. It would put even more of a crimp in her possible future relationship with Edward, though.)

On a side note, Chelsea's power is scary. Not just for its obvious nightmare-fuel, but for the cognitive implications. If it doesn't affect memory but still affects a person's evaluation of another's importance to them, then it must be either fundamentally changing their moral values such that even after reevaluating their memories, they do not feel that the other is important, or forcing the relationship-evaluating bit of their mind to evaluate to 'false' (or "Chelsea's chosen value", whatever) regardless of memory. But if it was the simple latter case, then a victim once they had left her immediate presence could undo most of the effect simply by reevaluating their memories and noting the things that make the other person important, which is evidently not the case. Thus, Chelsea is either fundamentally changing your sense of morality, or introducing irremovable inconsistencies into your relationship evaluation. Either way is awful.

Bella knew about Allirea's power and apparently remembered long enough to tell Elspeth about it.

Keyword being Bella. She's badass like that. :)

She noticed that Elspeth "announces her presence" loudly, which is a perception on the same scale.

Yes, but Allirea seems to effect people other than herself. And so if she hides Elspeth to everyone but Allirea, her perception of how "loud" Elspeth is won't change.

If things go pear-shaped, she just fades and tries something else.

That an error has relatively small cost (though don't forget opportunity cost), is no argument for making the error, when it could be just not made. It costs nothing to not make the error, so the costs of consequences of making the error are not relevant, as there is no tradeoff.

Edit: Also, the cost is not small for Elspeth, so this argument I disagree with doesn't even address one of the two idiot balls.

It doesn't, which Elspeth knows

It wasn't obvious that she can reliably feel the effect of lies on her power, and that there is a reliable dependence of efficiency of hiding-into-unimportance on Elspeth's perception of her power. The direct measurement is Allirea's sense of efficiency of hiding, and it's accessible to experiment, so it obviously should be tested (unless both of my questions in the first statement of this paragraph receive negative answers, which I can't see how can be done for the second one without testing).