Greetings! I am glad you asked about the proper way to address Christmas cards in the plural. It is important to be accurate and respectful when addressing multiple recipients. Here are some general guidelines:
1. For a group of people or a family, use "Dear All" or "Dear Family".
2. For a married couple, use "Dear Mr. and Mrs." followed by the couple's last name.
3. For unmarried couples, use "Dear Mr./Ms." followed by each person's first name and last name.
4. For a group of children, use "Dear Kids" or "Dear Children".