As Ireland converted to Christianity under St. Patrick, legends of magical creatures like fairies and leprechauns grew smaller until they were "wee people." Even mischeivous leprechauns honor St. Patrick by doing secret acts of kindness and your family can help.
Give everyone a handful of shamrocks (make or buy at a craft or fabric store) and have them look for opportunities to do secret acts of service and kindness anonymously. Mark the spot with a shamrock. At dinner on St. Patrick's Day, collect the shamrocks to sprinkle around the table and enjoy evidence of kind and loving deeds.