It can be nerve racking going to a family gathering and hoping your kids will be appreciative and use their manners. Preset your kids before going to the gathering and let them know what your expectations are. It's important that they understand that even if it's something they don't like, they should still use good manners, say thank you and show appreciation.
You can play "the manner game" to get your kids ready for showing their manners. Have your kids find things throughout the house and give a present to each other. When they open the gift(even if it's toilet paper), they must say thank you and something nice about it. This is a fun way to get your kids ready for the holidays!! Make using manners fun and of course praise them when they do a good job!