If the person you are inviting is engaged – it is proper etiquette to extend the invitation to the fiancé or significant other. According to proper etiquette, you should contact your single or engaged friends/ family and ask if they’d like to bring a guest and what is the name of the prospective guest (be sure to obtain the proper spelling of their name). However, it is understandable this can become a tedious task, therefore, the words “and guest” are acceptable when addressing invitations. Please note if you have an inner and outer envelope, the outer envelope should not state “and guest”, but rather the inner envelope should contain it (the only exception is if there is a single envelope, then it must go on that single envelope).
Inner Envelope Addressed Single and Guest: Sally Martin and guest OR Sally Martin and escort