Should they let them know that they are a year off now and save them embarassment later (aka when my dad throws my step-mom a party for her 50th or when we take my parents out to dinner for their 10th anniversary)? Or should they let them figure it out eventually by themselves (when invited to these parties, hearing from others, etc.)? How would you go about letting them know? My parents will be seeing them in person this upcoming weekend.
My parents are planning on telling them as soon as possible. They are going to make light of the mistake/joking about it/mentioning it offhand, but show sincere gratitude for the gift. The gift was perfect for them and the friends mean a lot to my family and were very sweet for thinking of them. They are thinking of making note of it in the thank you card, but they aren't sure because they will be seeing them before the thank you card makes it to their house.