1. (Rank fully written out) + His Name & Mrs. Her Name
Example: Seaman John Smith and Mrs. Mary Smith
Is anyone coming to your wedding that’s Navy enlisted? Because E4-E6 are Petty Officer, but they go by their rating (job), so it’s a little confusing. So, a PO 3rd class might be ET3 John Smith, or MM3, etc. But you would address it to “Petty Officer (Whatever Number) Class John Smith”.
Some etiquette sources say that enlisted do not get the rank listed before their name, just their branch of service underneath. However, if you’re inviting someone like a Chief or Sargeant Major, I sure would cause that’s pretty high up. I honestly would either way, though, and it’s not incorrect to include it per this website.
2. Do the brother and sister live in the same house? If so, I always was told to send separate invitations addressed separately, at least that’s how we did it. So, I’m not sure!
3. For boyfriend/girlfriend, we sent it to the couple putting his name first, but sent it to her address, unless they live together, then it doesn’t really matter. 🙂
4. For 2 sisters, still separate wedding invitations unless one sister is very young and could be considered to live in her sister’s household. In that case, I would send 1 invitation, but write their names: Maggie Jones and Sallie Jones on one invite.
If, however, they’re both adults, and/or you are friends with them separately, I would send 2 invitations just like the brother/sister.