Addressing STDs

Question regarding addressing STDs for unmarried friends who have boyfriends.

Do I address them as:

1. Miss/Ms. Lisa Smith and Mr. John Brown

2. Mr. John Brown and Miss/Ms. Lisa Smith

I am much closer with the girls, so I don't know if I should put their name first, or their boyfriend's name first. Also, for girls in their 20s, do I put Miss or Ms??

Thanks!!

Definitely Ms. for those girls...any over 16 really.

Etiquette says to put the person you're closer to first. :)