I have been formally addressing our invitations according to convention taking into account persons who are married, widowed, living together, same gender couples etc.
My finacé a member of a club of 25 gentlemen, all of whom are invited. The invitations are addressed to Mr. & Mrs. in the case of married, Mr. only in the case of singles or casual dating members of the club, or Ms. Brown and Mr. Jones (alphabetically by last name) in the case of living together couples.
Here's my question. My fiancé's ex wife has been dating one of the club members for so long, they're just a fixture in the group. They are both welcome at our wedding, but I don't know how to address the envelope. The do not live together, so convention would dictate the envelope get addressed just to him, but we don't want her to feel like she's not invited, but also it would look wierd to send her one separately. Suggestions? Her name comes before his alphabetically.