We are inviting FI's great aunt, who is a nun, to our wedding. FI's grandmother provided her mailing address for the out envelope as address to Sister Mary Jean Doe.
What is the correct way to address the inner envelope? I haven't had much luck finding a definitive answer online. Following the formula of title and last name, it would be Sister Doe. But Sister Mary feels more natural. FI's family commonly calls her Aunt Mary.
Does anyone know what the correct form for the inner envelope is? TIA