Ideas for a fun way to announce pregnancy of a small group at one time

My MIL is super unsupportive of anything my husband and I do, to the point that my husband does not even want to tell her we are expecting. We have been together for 7 years, own a home, are both educated, have good jobs, and are extremely excited about our new arrival. He gets anxiety just thinking about telling her, so we decided to have a small BBQ on Mother's day and invited his dad's family over who we know will be excited for us as a buffer. It is just his Grandma (who already knows and couldn't be more excited for us), his aunt, uncle, and their family. We are just trying to figure out a fun way to share our news that would include everyone and create excitement. Does anyone have a similar experience or a way they told a group of 11 or 12 people or just an idea of a way to tell them? Any ideas are much appreciated!