This is what I understand - but let me know if I'm mistaken - I just wanted to make sure:
- when inviting two people that live together, we address the outer envelope to both of them
- when inviting someone who has a significant other, but does not live with them, I address it to the person on the outer envelope, then on the inner envelope put both their names. (ie, I have a friend Trey who was engaged, but does not live with her. I don't really know her, but she would of course be invited. It is addressed just to him, but her name would go on the inner envelope.)
Does that seem correct?
Thanks!