You can create a game similar to the one played at showers:
Everyone gets a safety pin (with a bit of pretty fabric or even a 3"/4" square) to wear. Every time someone says: grandchild or mother or daughter-in-law (whatever fits the demographics of your group) the person that catches them gets the pin and the fabric square.
You could have them make a quilted item for the next retreat raffle.
K Cama