Addressing my one envelope invitations, and have come to several friends who will be invited with a plus one. As I do not have inner envelopes on which to write 'Ms. Jane Doe and Guest', can this go on the outer/only envelope? My reply cards will say _# seats have been reserved in your honour, so I don't know if the envelope even needs to say 'and Guest' as the reply card tells them they get two seats.
So...add 'and Guest' to the outer (and only) envelope, or, have one name on the envelope and trust they'll understand that by '_# seats' they have a plus one?