Family support

So earlier this week I put up a topic about creative ways to tell my family and friends about baby #3 on the way. I'm very worried about how my mother will react because she currently lives with my family and I (only 54) and its hard to be myself and talk to her on a mother/wife 
level. I want surprise them all but I don't think my mom will be as happy about it as everyone else. What do I do?