I know of 3 ways:
1. Mr. & Mrs.
2. Mom and Dad
3. First names
No.
Outlaws are wanted...... inlaws aren't.
Ask your spouse
petheriká
dear
No.
Inlaws.
The best way to verify an address is to use the Royal Mail's address or postcode finder, which can be found at www.royalmail.co.uk.
but your brother is her husbande
The best way to address your letter to a Minister is to Reverend and Mrs. _______
The best way to address the mayor is to call him mayor with his last name. This will demonstrate that you are professional and you know what to call him or her.
Sounds like a wonderful Wedding Present for the new inlaws. The Phantom of the Opera in Toronto will be perfect and enjoyable.