I have a question about wording the address for a particular situation. My cousins are sisters (same last name)that live together, not with their parents. They're both in their 20's. I am not letting them bring guests as they are both single. Should I send them one STD card with both their names on it or should I send them each one? If I can send just one, how do I word it? And is it the same for the invites? TIA!