I am the mom of the bride. The wedding was this past weekend. The groom's parents were major contributors in everything (at their request). They hosted the rehearsal dinner and a morning-after brunch. They also paid $10k towards the wedding. What is appropriate for me to show them how much we all appreciate what they did, as well as letting them know how happy we are to have them as part of our family? Is there any protocol for parents thanking parents?