I think very small bits of cheese is a great reward, and maybe that won't challenge you as much ethically.
It doesn't sound to me like your pup is misbehaving so much as GETTING INCREDIBLY EXCITED THAT NEW PEOPLE ARE HERE!!!!!!! and forgetting her manners. You've already gotten a lot of good advice.
Can you practice with small gatherings, maybe just one person to start so it's not such an overload with her? If she gets excited with your husband, he can practice with her. I saw on "It's Me or the Dog" that a dog can't pee if it's in Sit position, so if excitable peeing is a problem, make sure she's in a Sit.
When I go to the park with Thor, I make him Sit and Stay to earn his time off-leash. If he disobeys me once he gets off leash (examples: bugging strangers with food and not returning when I call to him, or not obeying Drop It on some disgusting food he he found) I put him back on the leash in the same place as I did originally, and he has Sit and Stay again. Usually one correction will do it, but if there are multiple infractions, we leave the park. Maybe you can set up something similar with your pup.
The main thing I would emphasize is to build up gradually so she can practice her impulse control. She's not a Bad Dog, she's just overly excited.
===================
Cheese IS constipating, so you can also try little bits of buttery green beans. Yorkies love green beans for some reason.