Hmm. I'd have to vote for Julius and Anna as the best way to get your "embarrassing moment" in without uniting them too quickly.And without completely shattering Lucy. Of course, I've never written a novel(except for a very sad little Tales of The City meets Butterflies are Free that I wrote at college. Not all bad, but so Not Ready for Prime Time.)

I have to say that I hate characters being humiliated for any reason. I'd suggest that no one find them

For high conflict I'd say go with what erika suggested.

Hmm. How about a variation of #5? As far as Lucy knows, she's not discovered, but one of the cousins catches her but doesn't interrupt, instead going to the others and telling them what she's seen and heard. That way, Lucy will be steeling herself for how to announce the engagement, only to be bushwhacked by the post-ball confrontation.

I agree with Anne.

Anne's suggestion does sound as though it has potential.

Anne is wise.

I have to say that I hate characters being humiliated for any reason. I'd suggest that no one find them

Well, the humiliation would largely be in Lucy's mind--in the eyes of all of the potential witnesses except Portia, her actions really aren't a problem as long as she and James intend to get married.

As far as Lucy knows, she's not discovered, but one of the cousins catches her but doesn't interrupt, instead going to the others and telling them what she's seen and heard.

I'd have to rework some of the logistics--maybe lose the heavy, creaky door, for example--but this has potential. The interpersonal dynamics among the cousins are such that any one of them who saw her would probably confront her first rather than telling the others, but I do like the idea. Especially if it's Julius.

Julius, though, might confront him with it, rather than her.

Hmm. I could probably work the logistics such that he wouldn't have the chance to confront James before the end of the evening, but could easily confront Lucy, because as family members they're staying at the same place.